Polyester laminate materials

ABSTRACT

This invention relates to methods and apparatus for making articles made of polyester, preferably polyethylene terephthalate (PET), having coated directly to at least one of the surfaces thereof one or more layers of thermoplastic material with good gas-barrier characteristics. In one preferred method and apparatus, preforms are injection molded, barrier-coated immediately thereafter, and remain on a mold portion for a time to speed cooling of the completed preform. Preferably the barrier-coated articles take the form of preforms coated by at least one layer of barrier material and the containers are blow-molded therefrom. Such barrier-coated containers are preferably of the type to hold beverages such as soft drinks, beer or juice. The preferred barrier materials have a lower permeability to oxygen and carbon dioxide than PET as well as key physical properties similar to PET. The materials and methods provide that the barrier layers have good adherence to PET, even during and after the blow molding process to form containers from preforms. Preferred barrier coating materials include poly(hydroxyamino ethers).

RELATED APPLICATION DATA

[0001] This application is a divisional of copending U.S. patentapplication Ser. No. 09/296,695, filed Apr. 21, 1999, which is acontinuation-in-part of U.S. patent application Ser. No. 09/147,971,filed Oct. 19, 1998, entitled BARRIER-COATED POLYESTER which is acontinuation-in-part of U.S. patent application Ser. No. 08/953,595,filed Oct. 17, 1997 and also claims priority under 35 U.S.C. § 119(e)from provisional application Serial No. 60/078,641, filed Mar.19, 1998.

BACKGROUND OF THE INVENTION

[0002] This invention relates to an apparatus and method for makingbarrier-coated polyesters, preferably barrier coated polyethyleneterephthalate (PET) and articles made therefrom. Preferably thebarrier-coated PET takes the form of preforms having at least one layerof a barrier material and the bottles blow-molded therefrom.

[0003] The use of plastic containers as a replacement for glass or metalcontainers in the packaging of beverages has become increasinglypopular. The advantages of plastic packaging include lighter weight,decreased breakage as compared to glass, and potentially lower costs.The most common plastic used in making beverage containers today is PET.Virgin PET has been approved by the FDA for use in contact withfoodstuffs. Containers made of PET are transparent, thin-walled,lightweight, and have the ability to maintain their shape bywithstanding the force exerted on the walls of the container bypressurized contents, such as carbonated beverages. PET resins are alsofairly inexpensive and easy to process.

[0004] Despite these advantages and its widespread use, there is aserious downside to the use of PET in thin-walled beverage containers:permeability to gases such as carbon dioxide and oxygen. These problemsare of particular importance when the bottle is small. In a smallbottle, the ratio of surface area to volume is large which allows for alarge surface for the gas contained within to diffuse through the wallsof the bottle. The permeability of PET bottles results in soft drinksthat go “flat” due to the egress of carbon dioxide, as well as beveragesthat have their flavor spoiled due to the ingress of oxygen. Because ofthese problems, PET bottles are not suitable for all uses desired byindustry, and for many of the existing uses, the shelf-life of liquidspackaged in PET bottles is shorter than desired.

[0005] U.S. Pat. No. 5,464,106 to Slat, et al, describes bottles formedfrom the blow molding of preforms having a barrier layer. The barriermaterials disclosed are polyethylene naphthalate, saran, ethylene vinylalcohol copolymers or acrylonitrile copolymers. In Slat's technique, thebarrier material and the material to form the inner wall of the preformare coextruded in the shape of a tube. This tube is then cut intolengths corresponding to the length of the preform, and is then placedinside a mold wherein the outer layer of the preform is injected overthe tube to form the finished preform. The preform may then beblow-molded to form a bottle. The drawbacks of this method are that mostof the barrier materials disclosed do not adhere well to PET, and thatthe process itself is rather cumbersome.

[0006] A family of materials with good barrier characteristics are thosedisclosed in U.S. Pat. No. 4,578,295 to Jabarin. Such barrier materialsinclude copolymers of terephthalic acid and isophthalic acid withethylene glycol and at least one diol. This type of material iscommercially available as B-010 from Mitsui Petrochemical Ind. Ltd.(Japan). These barrier materials are miscible with polyethyleneterephthalate and form blends of 80-90% PET and 10-20% of thecopolyester from which barrier containers are formed. The containersmade from these blends are about 20-40% better gas barriers to CO2transmission than PET alone. Although some have claimed that thispolyester adheres to PET without delamination, the only preforms orcontainers disclosed were made with blends of these materials.

[0007] Another group of materials, the polyamine-polyepoxides, have beenproposed for use as a gas-barrier coating. These materials can be usedto form a barrier coating on polypropylene or surface-treated PET, asdescribed in U.S. Pat. No. 5,489,455 to Nugent, Jr. et al. Thesematerials commonly come as a solvent or aqueous based thermosettingcomposition and are generally spray coated onto a container and thenheat-cured to form the finished barrier coating. Being thermosets, thesematerials are not conducive to use as preform coatings, because once thecoating has been cured, it can no longer be softened by heating and thuscannot be blow molded, as opposed to thermoplastic materials which canbe softened at any time after application.

[0008] Another type of barrier-coating, that disclosed in U.S. Pat. No.5,472,753 to Farha, relies upon the use of a copolyester to effectadherence between PET and the barrier material. Farha describes twotypes of laminates, a three-ply and a two-ply. In the three-plylaminate, an amorphous, thermoplastic copolyester is placed between thebarrier layer of phenoxy-type thermoplastic and the layer of PET toserve as a tie layer to bind the inner and outer layers. In the two-plylaminate, the phenoxy-type thermoplastic is first blended with theamorphous, thermoplastic copolyester and this blend is then applied tothe PET to form a barrier. These laminates are made either by extrusionor by injection molding wherein each layer is allowed to cool before theother layer of material is injected.

[0009] PCT Application Number PCT/US95/1701 1, to Collette et al., whichwas published on Jul. 4, 1996, describes a method of cooling multilayerpreforms. The disclosed apparatus comprises a rotary turret havingmultiple faces, each face carrying an array of cores. The cores areinserted into corresponding mold cavities. Multiple melt streams arebrought together and coinjected into each cavity to form a multilayerpreform on each core. After the preform is injected, the cores areremoved from the cavities and the turret is rotated, presenting a newset of cores to the mold cavities. The just-injected cavities remain onthe cores cooling while preforms are formed on other arrays of cores.The drawbacks of the Collette application include that coinjectionresults in preforms that are inconsistent and have unpredictablelayering. Thus, distribution of barrier materials in such a preformwould be unpredictable and would result in a preform having unreliablebarrier properties.

[0010] Since PET containers can be manufactured by injection moldingusing only a single injection of PET, manufacture is relatively easy andproduction cycle time is low. Thus, PET containers are inexpensive. Evenif known barrier materials can be bonded to PET to create a saleablecontainer with reliable barrier properties, methods and apparatus formaking such containers within a competitive cycle time and cost have notbeen devised. Production cycle time is especially important because alower cycle time enables a manufacturer to make more efficient use ofits capital equipment. Thus, low cycle time enables higher volume andless expensive production of containers. Cost-effective production wouldbe necessary to develop a viable alternative to monolayer PETcontainers.

[0011] Thus, the need exists for an apparatus and method for makingbarrier-coated PET preforms and containers which are economical,cosmetically appealing, easy to produce, and have good barrier andphysical properties remains unfulfilled.

SUMMARY OF THE INVENTION

[0012] This invention relates to methods and apparatus for making PETarticles having coated upon the surfaces thereof one or more thin layersof thermoplastic material with good gas-barrier characteristics. Thearticles of the present invention are preferably in the form of preformsand containers.

[0013] In an aspect of the present invention there is provided a barriercoated preform comprising a polyester layer and a barrier layercomprising barrier material, wherein the polyester layer is thinner inthe end cap than in the wall portion and the barrier layer is thicker inthe end cap than in the wall portion.

[0014] In another aspect of the present invention there is provided amethod for making a barrier coated polyester article. A polyesterarticle with at least an inner surface and an outer surface is formed byinjecting molten polyester through a first gate into the space definedby a first mold half and a core mold half, where the first mold half andthe core mold half are cooled by circulating fluid and the first moldhalf contacts the outer polyester surface and the core mold halfcontacts the inner polyester surface. Following this, the moltenpolyester is allowed to remain in contact with the mold halves until askin forms on the inner and outer polyester surfaces which surrounds acore of molten polyester. The first mold half is then removed from thepolyester article, and the skin on the outer polyester surface issoftened by heat transfer from the core of molten polyester, while theinner polyester surface is cooled by continued contact with the coremold half. The polyester article, still on the core mold half is thenplaced into a second mold half, wherein the second mold half is cooledby circulating fluid. In the coating step, the barrier layer comprisingbarrier material is placed on the outer polyester surface by injectingmolten barrier material through a second gate into the space defined bythe second mold half and the outer polyester surface to form the barriercoated polyester article. The second mold half is then removed from thebarrier coated article and then the barrier coated article is removedfrom the core mold half. The barrier materials used in the processpreferably comprise a Copolyester Barrier Materials, Phenoxy-typeThermoplastics, Polyamides, polyethylene naphthalate, polyethylenenaphthalate copolymers, polyethylene naphthalate/polyethyleneterephthalate blends, and combinations thereof.

[0015] In a further aspect of the present invention, there is provided amethod of making and coating preforms. The method begins by closing amold comprising a stationary half and a movable half, wherein thestationary mold half comprises at least one preform molding cavity andat least one preform coating cavity and the movable mold half comprisesa rotatable plate having mounted thereon a number of mandrels equal tothe sum of the number of preform molding cavities and preform coatingcavities. The remaining steps comprise: injecting a first material intothe space defined by a mandrel and a preform molding cavity to form apreform having an inner surface and an outer surface; opening the mold;rotating the rotatable plate; closing the mold; injecting a secondmaterial into the space defined by the outer surface of the preform andthe preform coating cavity to form a coated preform; opening the mold;removing the coated preform.

[0016] In accordance with a preferred embodiment having features inaccordance with the present invention, an apparatus for injectionmolding multilayer preforms is provided. The apparatus comprises firstand second mold cavities in communication with first and second meltsources, respectively. A turntable is provided and is divided into aplurality of stations, with at least one mold core disposed on eachstation. The turntable is adapted to rotate each station to a firstposition at which a core on the station interacts with the first moldcavity to form a first preform layer, then to a second position at whichthe core interacts with the second mold cavity to form a second preformlayer. Finally, the turntable is further adapted to rotate the stationto at least one cooling position, at which the molded preform remains onthe core to cool.

[0017] In accordance with another preferred embodiment having featuresin accordance with the present invention, a mold apparatus for injectionmolding multilayer preforms is provided. The mold apparatus has a firstmold body which is adapted to fit about a mold core to define a firstlayer cavity therebetween, a first gate area, and is in communicationwith a first melt source. A second mold body is adapted to fit about afirst preform layer disposed on the mold core to define a second layercavity therebetween, has a second gate area, and is in communicationwith a second melt source. At least one of the gate areas has Ampcoloymetal inserts disposed therein.

[0018] In accordance with another preferred embodiment having featuresin accordance with the present invention, a mold apparatus for injectionmolding multilayer preforms is provided. The mold apparatus has a firstmold body which is adapted to fit about a mold core, defining a firstlayer cavity therebetween. The first layer cavity has a base end and amain body. The first mold body is in communication with a first meltsource and has a first gate area adjacent the base end of the firstlayer cavity. A thickness of the cavity at the base end is less than thethickness of the main body of the cavity. the mold apparatus also has asecond mold body, which is adapted to fit about a first preform layerdisposed on the mold core, defining a second layer cavity therebetween.The second mold body is in communication with a second melt source andhas a second gate area.

[0019] In accordance with yet another preferred embodiment havingfeatures in accordance with the present invention, a mold for injectionmolding multilayer preforms is provided. The mold has a mandrel andfirst and second cavities. The mandrel is hollow and has a wall ofsubstantially uniform thickness. A coolant supply tube is disposedcentrally within the hollow mandrel to supply coolant directly to a baseend of the mandrel. The first cavity has a gate for injecting moltenplastic. A gate area of the cavity has an insert of material havinggreater heat transfer properties than the majority of the cavity.

[0020] In accordance with a further preferred embodiment having featuresin accordance with the present invention, a method for improvinginjection mold performance is provided. The method includes forming anopening in a wall of a mold cavity. The opening is sized and adapted sothat molten plastic will not substantially enter the opening. Apassageway is formed connecting the opening to a source of air pressure.The method further includes providing a valve between the opening andthe source of air pressure.

[0021] In accordance with another preferred embodiment having featuresin accordance with the present invention, a method for injection moldingand cooling a multilayer preform is provided. The method includes thesteps of providing a mold core disposed on a turntable and having aninternal cooling system, rotating the turntable so that the core isaligned with a first mold cavity, engaging the core with the first moldcavity, and injecting a melt to form a first preform layer. The firstpreform layer is held within the mold cavity to cool until a skin isformed on a surface of the layer, but an interior of the layer remainssubstantially molten. The core is then removed from the first moldcavity while retaining the molded preform layer on the core and theturntable is rotated so that the core is aligned with a second moldcavity. The core is engaged with the second mold cavity and a melt isinjected to form a second preform layer on top of the first preformlayer. The core is removed from the second mold cavity while retainingthe molded preform on the core and the turntable is rotated so that thecore and preform are in a cooling position during which the preformcools upon the core. The preform is eventually removed from the core.

[0022] In accordance with one aspect of the present invention, there isprovided a laminate comprising at least one layer of polyethyleneterephthalate directly adhered to at least one layer of barriermaterial. The polyethylene terephthalate has an isophthalic acid contentof at least about 2% by weight. Barrier materials used includeCopolyester Barrier Materials, Phenoxy-type Thermoplastics, Polyamides,polyethylene naphthalate, polyethylene naphthalate copolymers,polyethylene naphthalate/polyethylene terephthalate blends, andcombinations thereof. In preferred embodiments, the laminate is providedin the form of preforms and containers.

[0023] In accordance with a further aspect of the present invention,there is provided a preform comprising at least two layers, wherein thefirst layer is thinner in the end cap than in the wall portion and thesecond layer is thicker in the end cap than in the wall portion. Thefirst layer comprises polyethylene terephthalate having an isophthalicacid content of at least about 2% by weight and the second layercomprises a barrier material. Barrier materials used include CopolyesterBarrier Materials, Phenoxy-type Thermoplastics, Polyamides, polyethylenenaphthalate, polyethylene naphthalate copolymers, polyethylenenaphthalate/polyethylene terephthalate blends, and combinations thereof.

[0024] For purposes of summarizing the invention and the advantagesachieved over the prior art, certain objects and advantages of theinvention have been described hereinabove. Of course, it is to beunderstood that not necessarily all such objects or advantages may beachieved in accordance with any particular embodiment of the invention.Thus, for example, those skilled in the art will recognize that theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

[0025] All of these embodiments are intended to be within the scope ofthe invention herein disclosed. These and other embodiments of thepresent invention will become readily apparent to those skilled in theart from the following detailed description of the preferred embodimentshaving reference to the attached figures, the invention not beinglimited to any particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is an uncoated preform as is used as a starting materialfor embodiments of the present invention.

[0027]FIG. 2 is a cross-section of a preferred uncoated preform of thetype that is barrier-coated in accordance with an embodiment the presentinvention.

[0028]FIG. 3 is a cross-section of one preferred embodiment ofbarrier-coated preform of the present invention.

[0029]FIG. 4 is a cross-section of another preferred embodiment of abarrier-coated preform of an embodiment of the present invention.

[0030]FIG. 4A is an enlargement of a section of the wall portion of apreform such as that made by a LIM-over-inject process. Not all preformsof the type in FIG. 4 made in accordance with an embodiment of thepresent invention will have this type of layer arrangement.

[0031]FIG. 5 is a cross-section of another embodiment of abarrier-coated preform of an embodiment of the present invention.

[0032]FIG. 6 is a cross-section of a preferred preform in the cavity ofa blow-molding apparatus of a type that may be used to make a preferredbarrier-coated container of an embodiment of the present invention.

[0033]FIG. 7 is one preferred embodiment of barrier-coated container ofthe present invention.

[0034]FIG. 8 is a cross-section of one preferred embodiment of abarrier-coated container having features in accordance with the presentinvention.

[0035]FIG. 9 is a cross-section of an injection mold of a type that maybe used to make a preferred barrier-coated preform in accordance withthe present invention.

[0036]FIGS. 10 and 11 are two halves of a molding machine to makebarrier-coated preforms.

[0037]FIGS. 12 and 13 are two halves of a molding machine to makeforty-eight two-layer preforms.

[0038]FIG. 14 is a perspective view of a schematic of a mold withmandrels partially located within the molding cavities.

[0039]FIG. 15 is a perspective view of a mold with mandrels fullywithdrawn from the molding cavities, prior to rotation.

[0040]FIG. 16 is a three-layer embodiment of a preform.

[0041]FIG. 17 is a front view of a preferred embodiment of an apparatusfor making preforms in accordance with the present invention;

[0042]FIG. 18 is a cross-section of the apparatus of FIG. 17 taken alonglines 18-18;

[0043]FIG. 19 is a chart showing the relative positions of stations ofthe apparatus of FIG. 17 during a production cycle;

[0044]FIG. 20 is a front view of another preferred embodiment of anapparatus for making preforms in accordance with the present invention;

[0045]FIG. 21 is a close up view of a station and actuator of theapparatus of FIG. 20;

[0046]FIG. 22 is a front view of another preferred embodiment of anapparatus for making preforms in accordance with the present invention;

[0047]FIG. 23 is a front view of the apparatus of FIG. 22 in a closedposition;

[0048]FIG. 24 is a chart showing the relative positions of stations ofthe apparatus of FIG. 22 during a production cycle;

[0049]FIG. 25 is a schematic of a lamellar injection molding (LIM)system.

[0050]FIG. 26 is a cross-section of an injection mold of a type that maybe used to make a preferred preform of the present invention;

[0051]FIG. 27 is a cross-section of the mold of FIG. 26 taken alonglines 27-27;

[0052]FIG. 28 is a cutaway close up view of the area of FIG. 26 definedby line 28.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A. General Descriptionof the Invention

[0053] This invention relates to methods and apparatus for makingplastic articles having coatings comprising one or more layers ofthermoplastic material with good gas-barrier characteristics. Aspresently contemplated, one embodiment of barrier coated article is abottle of the type used for beverages. Alternatively, embodiments of thebarrier coated articles of the present invention could take the form ofjars, tubs, trays, or bottles for holding liquid foods. However, for thesake of simplicity, these embodiments will be described herein primarilyin the context of beverage bottles and the preforms from which they aremade by blow-molding.

[0054] Furthermore, the invention is described herein specifically inrelation to polyethylene terephthalate (PET) but it is applicable tomany other thermoplastics of the polyester type. Examples of such othermaterials include polyethylene 2,6-and 1,5-naphthalate (PEN), PETG,polytetramethylene 1,2-dioxybenzoate and copolymers of ethyleneterephthalate and ethylene isophthalate.

[0055] In especially preferred embodiments, “high IPA PET” is used asthe polyester which is barrier coated. As it is used herein, the term“high-IPA PET” refers to PET to which IPA was added during tomanufacture to form a copolymer in which the IPA content is more thanabout 2% by weight, preferably 2-10% IPA by weight, more preferably3-8%, most preferably about 4-5% IPA by weight. The most preferred rangeis based upon current FDA regulations, which do not allow for PETmaterials having an IPA content of more than 5% to be in contact withfood or drink. If such regulations are not a concern, then an IPAcontent of 5-10% is preferred. As used herein, “PET” includes “high IPAPET.”

[0056] The high-IPA PET (more than about 2% by weight) is preferredbecause the inventor has surprisingly discovered that use of high-IPAPET in the processes for making barrier preforms and containers,provides for better interlayer adhesion than is found in those laminatescomprising PET with no IPA or low IPA. Additionally, it has been foundthat interlayer adhesion improves as the IPA content rises.Incorporation of the higher amounts of IPA into the PET results in adecrease in the rate of crystallization of the high IPA PET material ascompared to PET homopolymer, or PET having lower amounts of IPA. Thedecrease in the rate of crystallization allows for the production of PETlayers (made of high IPA PET) having a lower level of crystallinity thanwhat is achieved with low-IPA PET or homopolymer PET when they are madeinto barrier preforms by similar procedures. The lower crystallinity ofthe high-IPA PET is important in reducing crystallinity at the surfaceof the PET, i.e. the interface between the PET and the barrier material.Lower crystallinity allows for better adhesion between the layers andalso provides for a more transparent container following blow molding ofthe preform.

[0057] Preferably, the preforms and containers have the barrier coatingdisposed on their outer surfaces or within the wall of the container. Incontrast with the technique of Slat, which produces multilayeredpreforms in which the layers are readily separated, in embodiments ofthe present invention the thermoplastic barrier material adheresdirectly and strongly to the PET surface and is not easily separatedtherefrom. Adhesion between the layers results without the use of anyadditional materials such as an adhesive material or a tie layer. Thecoated preforms are processed, preferably by stretch blow molding toform bottles using methods and conditions similar to those used foruncoated PET preforms. The containers which result are strong, resistantto creep, and cosmetically appealing as well as having good gas-barrierproperties.

[0058] One or more layers of a barrier material are employed in carryingout the present invention. As used herein, the terms “barrier material”,“barrier resin” and the like refer to materials which, when used to formarticles, preferably have key physical properties similar to PET, adherewell to PET, and have a lower permeability to oxygen and carbon dioxidethan PET.

[0059] Once a suitable barrier material is chosen, an apparatus andmethod for economically manufacturing a container using the barriermaterial is necessary. One important method and apparatus involves usingan injection molding machine in conjunction with a mold comprising amandrel or core and a cavity. A first layer of a preform is moldedbetween the mandrel and a first cavity of the mold when a moltenpolyester is injected therein. The first layer remains on the mandrelwhen the mandrel is pulled out of the cavity, moved, and inserted into asecond mold cavity. A second layer of the material, preferably a barrierlayer or a layer comprising barrier material, is then injected over theexisting first preform layer. The mandrel and accompanying preform arethen removed from the second cavity and a robot removes the preform fromthe mandrel. While the robot cools the molded preform, the mandrel isavailable for another molding cycle.

[0060] In another embodiment, the apparatus retains the preform on themandrel after removal from the second mold cavity but indexes themandrel out of the way of the mold cavities in order to cool the newpreform. During this time, other mandrels of the apparatus interact withthe mold cavities to form preform layers. After the preform issufficiently cooled, it is removed from the mandrel by a robot or otherdevice and the mandrel is available to start the process over again.This method and apparatus allows preforms to be cooled on the mandrelwithout substantially increasing cycle time.

[0061] A number of barrier materials having the requisite lowpermeability to gases such as oxygen and carbon dioxide are useful inembodiments of the present invention, the choice of barrier materialbeing partly dependent upon the mode or application as described below.Preferred barrier materials for use in barrier coatings fall into twomajor categories: (1) copolyesters of terephthalic acid, isophthalicacid, and at least one diol having good barrier properties as comparedto PET, such as those disclosed in U.S. Pat. No. 4,578,295 to Jabarin,and which is commercially available as B-010 (Mitsui Petrochemical Ind.Ltd., Japan); and (2) hydroxy-functional poly(amide-ethers) such asthose described in U.S. Pat. Nos. 5,089,588 and 5,143,998, poly(hydroxyamide ethers) such as those described in U.S. Pat. No. 5,134,218,polyethers such as those described in U.S. Pat. Nos. 5,115,075 and5,218,075, hydroxy-functional polyethers such as those as described inU.S. Pat. No. 5,164,472, hydroxy-functional poly(ether sulfonamides)such as those described in U.S. Pat. No. 5,149,768, poly(hydroxy esterethers) such as those described in U.S. Pat. No. 5,171,820,hydroxy-phenoxyether polymers such as those described in U.S. Pat. No.5,814,373, and poly(hydroxyamino ethers) (“PHAE”) such as thosedescribed in U.S. Pat. No. 5,275,853. The barrier materials described in(1) above are referred to herein by the term “Copolyester BarrierMaterials”. The compounds described in the patents in (2) above arecollectively categorized and referred to herein by the term“Phenoxy-type Thermoplastic” materials. All the patents referenced inthis paragraph are hereby incorporated in their entireties into thisdisclosure by this reference thereto.

[0062] Preferred Copolyester Barrier Materials will have FDA approval.FDA approval allows for these materials to be used in containers wherethey are in contact with beverages and the like which are intended forhuman consumption. To the inventor's knowledge, none of the Phenoxy-typeThermoplastics have FDA approval as of the date of this disclosure.Thus, these materials are preferably used in multi-layered containers inlocations which do not directly contact the contents, if the contentsare ingestible.

[0063] In carrying out preferred methods of the present invention toform barrier coated preforms and bottles, an initial preform is coatedwith at least one additional layer of material comprising barriermaterial, polyesters such as PET, post-consumer or recycled PET(collectively recycled PET), and/or other compatible thermoplasticmaterials. A coating layer may comprise a single material, a mix orblend of materials (heterogeneous or homogeneous), an interwoven matrixof two or more materials, or a plurality of microlayers (lamellae)comprised of at least two different materials. In one embodiment, theinitial preform comprises a plurality of microlayers, such as may beprepared by a lamellar injection molding process. Initial preformscomprise polyester, and it is especially preferred that initial preformscomprise virgin materials which are approved by the FDA for being incontact with foodstuffs.

[0064] Thus the preforms and containers of embodiments of the presentinvention may exist in several embodiments, such as: virgin PET coatedwith a layer of barrier material; virgin PET coated with a layer ofmaterial comprising alternating microlayers of barrier material andrecycled PET; virgin PET coated with a barrier layer which is in turncoated with recycled PET; microlayers of virgin PET and a barriermaterial coated with a layer of recycled PET; or virgin PET coated withrecycled PET which is then coated with barrier material. In any case, atleast one layer must comprise at least one barrier material.

[0065] As described previously, preferred barrier materials for use inaccordance with the present invention are Copolyester Barrier Materialsand Phenoxy-type Thermoplastics. Other barrier materials having similarproperties may be used in lieu of these barrier materials. For example,the barrier material may take the form of other thermoplastic polymers,such as acrylic resins including polyacrylonitrile polymers,acrylonitrile styrene copolymers, polyamides, polyethylene naphthalate(PEN), PEN copolymers, and PET/PEN blends. Preferred barrier materialsin accordance with embodiments of the present invention have oxygen andcarbon dioxide permeabilities which are less than one-third those ofpolyethylene terephthalate. For example, the Copolyester BarrierMaterials of the type disclosed in the aforementioned patent to Jabarinwill exhibit a permeability to oxygen of about 11 cc mil/100 in² day anda permeability to carbon dioxide of about 2 cc mil/100 in² day. Forcertain PHAEs, the permeability to oxygen is less than 1 cc mil/100 in²day and the permeability to carbon dioxide is 3.9 cc mil/100 in² day.The corresponding CO₂ permeability of polyethylene terephthalate,whether in the recycled or virgin form, is about 12-20 cc mil/100 in²day.

[0066] The methods of embodiments of the present invention provide for acoating to be placed on a preform which is later blown into a bottle.Such methods are preferable to placing coatings on the bottlesthemselves. Preforms are smaller in size and of a more regular shapethan the containers blown therefrom, making it simpler to obtain an evenand regular coating. Furthermore, bottles and containers of varyingshapes and sizes can be made from preforms of similar size and shape.Thus, the same equipment and processing can be used to produce preformsto form several different kinds of containers. The blow-molding may takeplace soon after molding, or preforms may be made and stored for laterblow-molding. If the preforms are stored prior to blow-molding, theirsmaller size allows them to take up less space in storage.

[0067] Even though it is preferable to form containers from coatedpreforms as opposed to coating containers themselves, they havegenerally not been used because of the difficulties involved in makingcontainers from coated or multi-layer preforms. One step where thegreatest difficulties arise is during the blow-molding process to formthe container from the preform. During this process, defects such asdelamination of the layers, cracking or crazing of the coating, unevencoating thickness, and discontinuous coating or voids can result. Thesedifficulties can be overcome by using suitable barrier materials andcoating the preforms in a manner that allows for good adhesion betweenthe layers.

[0068] Thus, one aspect of the present invention is the choice of asuitable barrier material. When a suitable barrier material is used, thecoating sticks directly to the preform without any significantdelamination, and will continue to stick as the preform is blow-moldedinto a bottle and afterwards. Use of a suitable barrier material alsohelps to decrease the incidence of cosmetic and structural defects whichcan result from blow-molding containers as described above.

[0069] It should be noted that although most of the discussion,drawings, and examples of making coated preforms deal with two layerpreforms, such discussion is not intended to limit the present inventionto two layer articles. The two layer barrier containers and preforms ofthe present invention are suitable for many uses and are cost-effectivebecause of the economy of materials and processing steps. However, insome circumstances and for some applications, preforms consisting ofmore than two layers may be desired. Use of three or more layers allowsfor incorporation of materials such as recycled PET, which is generallyless expensive than virgin PET or the preferred barrier materials. Thus,it is contemplated as part of the present invention that all of themethods for producing the barrier-coated preforms of the presentinvention which are disclosed herein and all other suitable methods formaking such preforms may be used, either alone or in combination toproduce barrier-coated preforms and containers comprised of two or morelayers.

B. Detailed Description of the Drawings

[0070] Referring to FIG. 1, a preferred uncoated preform 30 is depicted.The preform is preferably made of an FDA approved material such asvirgin PET and can be of any of a wide variety of shapes and sizes. Thepreform shown in FIG. 1 is of the type which will form a 16 oz.carbonated beverage bottle that requires an oxygen and carbon dioxidebarrier, but as will be understood by those skilled in the art, otherpreform configurations can be used depending upon the desiredconfiguration, characteristics and use of the final article. Theuncoated preform 30 may be made by injection molding as is known in theart or by methods disclosed herein.

[0071] Referring to FIG. 2, a cross-section of the preferred uncoatedpreform 30 of FIG. 1 is depicted. The uncoated preform 30 has a neckportion 32 and a body portion 34. The neck portion 32 begins at theopening 36 to the interior of the preform 30 and extends to and includesthe support ring 38. The neck portion 32 is further characterized by thepresence of the threads 40, which provide a way to fasten a cap for thebottle produced from the preform 30. The body portion 34 is an elongatedand cylindrically shaped structure extending down from the neck portion32 and culminating in the rounded end cap 42. The preform thickness 44will depend upon the overall length of the preform 30 and the wallthickness and overall size of the resulting container.

[0072] Referring to FIG. 3, a cross-section of one type ofbarrier-coated preform 50 having features in accordance with the presentinvention is disclosed. The barrier-coated preform 50 has a neck portion32 and a body portion 34 as in the uncoated preform 30 in FIGS. 1 and 2.The barrier coating layer 52 is disposed about the entire surface of thebody portion 34, terminating at the bottom of the support ring 38. Abarrier coating layer 52 in the embodiment shown in the figure does notextend to the neck portion 32, nor is it present on the interior surface54 of the preform which is preferably made of an FDA approved materialsuch as PET. The barrier coating layer 52 may comprise either a singlematerial or several microlayers of at least two materials. The overallthickness 56 of the preform is equal to the thickness of the initialpreform plus the thickness 58 of the barrier layer, and is dependentupon the overall size and desired coating thickness of the resultingcontainer. By way of example, the wall of the bottom portion of thepreform may have a thickness of 3.2 millimeters; the wall of the neckfinish, a cross-sectional dimension of about 3 millimeters; and thebarrier material applied to a thickness of about 0.3 millimeters.

[0073] Referring to FIG. 4, a preferred embodiment of a coated preform60 is shown in cross-section. The primary difference between the coatedpreform 60 and the coated preform 50 in FIG. 3 is the relative thicknessof the two layers in the area of the end cap 42. In coated preform 50,the barrier layer 52 is generally thinner than the thickness of theinitial preform throughout the entire body portion of the preform. Incoated preform 60, however, the barrier coating layer 52 is thicker at62 near the end cap 42 than it is at 64 in the wall portion 66, andconversely, the thickness of the inner polyester layer is greater at 68in the wall portion 66 than it is at 70, in the region of the end cap42. This preform design is especially useful when the barrier coating isapplied to the initial preform in an overmolding process to make thecoated preform, as described below, where it presents certain advantagesincluding that relating to reducing molding cycle time. These advantageswill be discussed in more detail below. The barrier coating layer 52 maybe homogeneous or it may be comprised of a plurality of microlayers.

[0074]FIG. 4A is an enlargement of a wall section of the preform showingthe makeup of the layers in a LIM-over-inject embodiment of preform. TheLIM process will be discussed in more detail below. The layer 72 is theinner layer of the preform and 74 is the outer layer of the preform. Theouter layer 74 comprises a plurality of microlayers of material as willbe made when a LIM system is used. Not all preforms of FIG. 4 will be ofthis type.

[0075] Referring to FIG. 5, another embodiment of a coated preform 76 isshown in cross-section. The primary difference between the coatedpreform 76 and the coated preforms 50 and 60 in FIGS. 3 and 4,respectively, is that the barrier coating layer 52 is disposed on theneck portion 32 as well as the body portion 34.

[0076] The barrier preforms and containers can have layers which have awide variety of relative thicknesses. In view of the present disclosure,the thickness of a given layer and of the overall preform or container,whether at a given point or over the entire container, can be chosen tofit a coating process or a particular end use for the container.Furthermore, as discussed above in regard to the barrier coating layerin FIG. 3, the barrier coating layer in the preform and containerembodiments disclosed herein may comprise a single material or severalmicrolayers of two or more materials.

[0077] After a barrier-coated preform, such as that depicted in FIG. 3,is prepared by a method and apparatus such as those discussed in detailbelow, it is subjected to a stretch blow-molding process. Referring toFIG. 6, in this process a barrier-coated preform 50 is placed in a mold80 having a cavity corresponding to the desired container shape. Thebarrier-coated preform is then heated and expanded by stretching and byair forced into the interior of the preform 50 to fill the cavity withinthe mold 80, creating a barrier-coated container 82. The blow moldingoperation normally is restricted to the body portion 34 of the preformwith the neck portion 32 including the threads, pilfer ring, and supportring retaining the original configuration as in the preform.

[0078] Referring to FIG. 7, there is disclosed an embodiment of barriercoated container 82 in accordance with the present invention, such asthat which might be made from blow molding the barrier coated preform 50of FIG. 3. The container 82 has a neck portion 32 and a body portion 34corresponding to the neck and body portions of the barrier-coatedpreform 50 of FIG. 3. The neck portion 32 is further characterized bythe presence of the threads 40 which provide a way to fasten a cap ontothe container.

[0079] When the barrier-coated container 82 is viewed in cross-section,as in FIG. 8, the construction can be seen. The barrier coating 84covers the exterior of the entire body portion 34 of the container 82,stopping just below the support ring 38. The interior surface 86 of thecontainer, which is made of an FDA-approved material, preferably PET,remains uncoated so that only the interior surface 86 is in contact withbeverages or foodstuffs. In one preferred embodiment that is used as acarbonated beverage container, the thickness 87 of the barrier coatingis preferably 0.020-0.060 inch, more preferably 0.030-0.040 inch; thethickness 88 of the PET layer is preferably 0.080-0.160 inch, morepreferably 0.100-0.140 inch; and the overall wall thickness 90 of thebarrier-coated container 82 is preferably 0.140-0.180 inch, morepreferably 0.150-0.170 inch. Preferably, on average, the overall wallthickness 90 of the container 82 derives the majority of its thicknessfrom the inner PET layer.

[0080]FIG. 9 illustrates a preferred type of mold for use in methodswhich utilize overmolding. The mold comprises two halves, a cavity half92 and a mandrel half 94. The cavity half 92 comprises a cavity in whichan uncoated preform is placed. The preform is held in place between themandrel half 94, which exerts pressure on the top of the preform and theledge 96 of the cavity half 92 on which the support ring 38 rests. Theneck portion 32 of the preform is thus sealed off from the body portionof the preform. Inside the preform is the mandrel 98. As the preformsits in the mold, the body portion of the preform is completelysurrounded by a void space 100. The preform, thus positioned, acts as aninterior die mandrel in the subsequent injection procedure, in which themelt of the overmolding material is injected through the gate 102 intothe void space 100 to form the coating. The melt, as well as theuncoated preform, is cooled by fluid circulating within channels 104 and106 in the two halves of the mold. Preferably the circulation inchannels 104 is completely separate from the circulation in the channels106.

[0081]FIGS. 10 and 11 are a schematic of a portion of the preferred typeof apparatus to make coated preforms in accordance with the presentinvention. The apparatus is an injection molding system designed to makeone or more uncoated preforms and subsequently coat the newly-madepreforms by over-injection of a barrier material. FIGS. 10 and 11illustrate the two halves of the mold portion of the apparatus whichwill be in opposition in the molding machine. The alignment pegs 110 inFIG. 10 fit into their corresponding receptacles 112 in the other halfof the mold.

[0082] The mold half depicted in FIG. 11 has several pairs of moldcavities, each cavity being similar to the mold cavity depicted in FIG.9. The mold cavities are of two types: first injection preform moldingcavities 114 and second injection preform coating cavities 120. The twotypes of cavities are equal in number and are preferably arranged sothat all cavities of one type are on the same side of the injectionblock 124 as bisected by the line between the alignment peg receptacles112. This way, every preform molding cavity 114 is 180° away from apreform coating cavity 120.

[0083] The mold half depicted in FIG. 10 has several mandrels 98, onefor each mold cavity (114 and 120). When the two halves which are FIGS.10 and 11 are put together, a mandrel 98 fits inside each cavity andserves as the mold for the interior of the preform for the preformmolding cavities 114 and as a centering device for the uncoated preformsin preform coating cavities 120. The mandrels 98 are mounted on aturntable 130 which rotates 180° about its center so that a mandrel 98originally aligned with a preform molding cavity 114 will, afterrotation, be aligned with a preform coating cavity 120, and vice-versa.As described in greater detail below, this type of setup allows apreform to be molded and then coated in a two-step process using thesame piece of equipment.

[0084] It should be noted that the drawings in FIGS. 10 and 11 aremerely illustrative. For instance, the drawings depict an apparatushaving three molding cavities 114 and three coating cavities 120 (a 3/3cavity machine). However, the machines may have any number of cavities,as long as there are equal numbers of molding and coating cavities, forexample 12/12, 24/24, 48/48 and the like. The cavities may be arrangedin any suitable manner, as can be determined by one skilled in the art.These and other minor alterations are contemplated as part of thisinvention.

[0085] The two mold halves depicted in FIGS. 12 and 13 illustrate anembodiment of a mold of a 48/48 cavity machine as discussed for FIGS. 10and 11.

[0086] Referring to FIG. 14 there is shown a perspective view of a moldof the type for an overmolding (inject-over-inject) process in which themandrels 98 are partially located within the cavities 114 and 120. Thearrow shows the movement of the movable mold half 142, on which themandrels 98 lie, as the mold closes.

[0087]FIG. 15 shows a perspective view of a mold of the type used in anovermolding process, wherein the mandrels 98 are fully withdrawn fromthe cavities 114 and 120. The arrow indicates that the turntable 130rotates 180° to move the mandrels 98 from one cavity to the next. On thestationary half 144, the cooling for the preform molding cavity 114 isseparate from the cooling for the preform coating cavity 120. Both ofthese are separate from the cooling for the mandrels 98 in the movablehalf.

[0088] Referring to FIG. 16 there is shown a preferred three-layerpreform 132. This embodiment of coated preform is preferably made byplacing two coating layers 134 and 136 on a preform 30 such as thatshown in FIG. 1.

[0089]FIG. 17 schematically shows another preferred apparatus 150 whichmay be used in an overmolding process. A first and second injector 152,154 are disposed at the top of the machine 150 to provide a meltstreamto first and second mold cavities 156, 158. FIG. 18 shows a rotatingtable 160 portion of the embodiment of FIG. 17. Four stations, labeled Athrough D, each have a mandrel 98A-D formed thereon and are disposed onthe rotating table 160 roughly 90° in rotation apart. An actuator 162such as a hydraulic cylinder lifts the table 160 so that mandrels 98from two stations are simultaneously inserted into the first and secondmold cavities 156, 158. The mandrels 98 on the other stations remainclear of any mold cavities. After the table 160 is lowered so that themandrels 98 are removed from the cavities, it then rotates 90°. Thus,the mandrel 98 that was just removed from the first cavity 156 is placedin position to be inserted into the second mold cavity 158 and themandrel just removed from the second cavity 158 is moved clear of themold cavities. Each of the stations are cycled in turn through the firstand second mold cavities 156, 158 by a series of sequential 90°rotations. FIG. 19 tracks the positions of the stations relative to eachother during each step of a production cycle.

[0090]FIGS. 20 and 21 show another embodiment of an apparatus 170 of thepresent invention similar in many ways to that of FIGS. 17 and 18.However, in this embodiment, instead of the entire table 160 beinglifted by a hydraulic member, each station of the turntable 160 isindividually controlled by an actuator 172, and independently moved intoand out of engagement with a respective mold cavity. This arrangementallows for increased flexibility of the apparatus 170. For example, FIG.20 shows that a mandrel 98 may be held within the second cavity 158after a mandrel 98 in the first cavity 156 is removed therefrom. Thus,hold time between mold cavities can be independently optimized.

[0091] With next reference to FIGS. 22-23, a schematic view of anotherpreferred apparatus 250 which may be used to overmold multilayerpreforms is shown. In this embodiment, a rotating turntable 260 has astation (AA-DD) formed on each of four sides. Mold mandrels 98 or coresare disposed on each of the stations as in previous embodiments. Firstand second mold cavities 256, 258 are in communication withcorresponding first and second injection machines 252, 254 which supplymelt streams of PET and barrier material, respectively. The first moldcavity 256 is connected to the first injection machine 252 and remainsstationary; the second injection machine 254 is vertically orientedoverhead and also remains stationary. The turntable 260 is supported bya base member 264 which is horizontally movable upon ways 266 whichsupport the base member 264. The second mold cavity 258 is connected tothe turntable 260 by actuators 268 and also moves horizontally with theturntable 260. The actuators 268 pull the second mold cavity 258 intoengagement with a mandrel 98B disposed on the turntable 268 in order toclose the mold. After the second cavity 258 engages the correspondingmandrel, the turntable 260 next moves horizontally to engage a mandrelwith the first mold cavity 256. With both mold cavities engaged withmandrels, the mold is now completely closed, as shown in FIG. 23. Also,the second injection machine 254 is placed in communication with thesecond mold cavity 258 so that the second injection machine 254 canprovide a melt stream of barrier material thereto.

[0092] When injection is complete, the mold is opened. This isaccomplished by the turntable 260 first moving horizontally to disengagethe mandrel from the first cavity 256, then raising the second mold outof engagement with the turntable 260. The turntable 260 then rotates 90°and closure of the mold and injection of material is repeated. Injectedpreforms disposed on the mandrels 98 not engaged with mold cavities coolupon the associated mandrel during the rest of the cycle. The preformsare ejected before the associated mandrel is again brought intoengagement with the first mold cavity 256. FIG. 24 tracks the positionsof the stations relative to each other during each step of a productioncycle.

[0093] Referring to FIG. 25, there is shown a schematic of an apparatuswhich may be used to produce a meltstream comprised of numerousmicrolayers or lamellae in a lamellar injection molding (LIM) process asdescribed in further detail below.

[0094] With next reference to FIG. 26, a preferred embodiment of a moldmandrel 298 and associated cavity 300 are shown. Cooling tubes 302 areformed in a spiral fashion just below the surface 304 of the mold cavity300. A gate area 308 of the cavity 300 is defined near a gate 308 and aninsert 310 of a material with especially high heat transfer propertiesis disposed in the cavity at the gate area 306. Thus, the injectedpreform's gate area/base end 314 is cooled especially quickly.

[0095] The mandrel 298 is hollow and has a wall 320 of generally uniformthickness. A bubbler cooling arrangement 330 is disposed within thehollow mandrel 298 and comprises a core tube 332 located centrallywithin the mandrel 298 which delivers chilled coolant C directly to abase end 322 of the mandrel 298. Coolant C works its way up the mandrelfrom the base end 322 and exits through an output line 334. The coretube is held in place by ribs 336 extending between the tube and themandrel wall 320.

[0096] Referring also to FIGS. 27 and 28, an air insertion system 340 isshown formed at a joint 342 between members of the mold cavity 300. Anotch 344 is formed circumferentially around the cavity 300. The notch344 is sufficiently small that substantially no molten plastic willenter during melt injection. An air line 350 connects the notch 344 to asource of air pressure and a valve regulates the supply of air to thenotch 344. During melt injection, the valve is closed. When injection iscomplete, the valve is opened and pressurized air A is supplied to thenotch 344 in order to defeat a vacuum that may form between an injectedpreform and the cavity wall 304.

[0097] The preferred method and apparatus for making barrier coatedpreforms is discussed in more detail below. Because the methods andapparatus are especially preferred for use in forming barrier coatedbottles comprising certain preferred materials, the physicalcharacteristics, identification, preparation and enhancement of thepreferred materials is discussed prior to the preferred methods andapparatus for working with the materials.

C. Physical Characteristics of Preferred Barrier Materials

[0098] Preferred barrier materials in accordance with the presentinvention preferably exhibit several physical characteristics whichallow for the barrier coated bottles and articles of the presentinvention to be able to withstand processing and physical stresses in amanner similar or superior to that of uncoated PET articles, in additionto producing articles which are cosmetically appealing and haveexcellent barrier properties.

[0099] Adhesion is the union or sticking together of two surfaces. Theactual interfacial adhesion is a phenomenon which occurs at themicroscopic level. It is based upon molecular interactions and dependsupon chemical bonding, van der Waals forces and other intermolecularattractive forces at the molecular level.

[0100] Good adhesion between the barrier layer and the PET layer isespecially important when the article is a barrier bottle made byblow-molding a preform. If the materials adhere well, then they will actas one unit when they are subjected to a blow molding process and asthey are subjected to stresses when existing in the form of a container.Where the adhesion is poor, delamination results either over time orunder physical stress such as squeezing the container or the containerjostling during shipment. Delamination is not only unattractive from acommercial standpoint, it may be evidence of a lack of structuralintegrity of the container. Furthermore, good adhesion means that thelayers will stay in close contact when the container is expanded duringthe molding process and will move as one unit. When the two materialsact in such a manner, it is less likely that there will be voids in thecoating, thus allowing a thinner coating to be applied. The barriermaterials preferably adhere sufficiently to PET such that the barrierlayer cannot be easily pulled apart from the PET layer at 22° C.

[0101] Thus, due in part to the direct adhesion of the barrier layer tothe PET, the present invention differs from that disclosed by Farha inU.S. Pat. No. 5,472,753. In Farha, there is not disclosed, nor is thesuggestion made, that the phenoxy-type thermoplastic can or should bebound directly to the PET without being blended with the copolyester orusing the copolyester as a tie layer or that a copolyester itself couldbe used as a barrier material.

[0102] The glass transition temperature (Tg) is defined as thetemperature at which a non-crystallizable polymer undergoes thetransformation from a soft rubber state to a hard elastic polymer glass.In a range of temperatures above its Tg, a material will become softenough to allow it to flow readily when subjected to an external forceor pressure, yet not so soft that its viscosity is so low that it actsmore like a liquid than a pliable solid. The temperature range above Tgis the preferred temperature range for performing a blow-moldingprocess, as the material is soft enough to flow under the force of theair blown into the preform to fit the mold but not so soft that itbreaks up or becomes uneven in texture. Thus, when materials havesimilar glass transition temperatures, they will have similar preferredblowing temperature ranges, allowing the materials to be processedtogether without compromising the performance of either material.

[0103] In the blow-molding process to produce bottle from a preform, asis known in the art, the preform is heated to a temperature slightlyabove the Tg of the preform material so that when air is forced into thepreform's interior, it will be able to flow to fill the mold in which itis placed. If one does not sufficiently heat the preform and uses atemperature below the Tg, the preform material will be too hard to flowproperly, and would likely crack, craze, or not expand to fill the mold.Conversely, if one heats the preform to a temperature well above the Tg,the material would likely become so soft that it would not be able tohold its shape and would process improperly.

[0104] If a barrier coating material has a Tg similar to that of PET, itwill have a blowing temperature range similar to PET. Thus, if a PETpreform is coated with such a barrier material, a blowing temperaturecan be chosen that allows both materials to be processed within theirpreferred blowing temperature ranges. If the barrier coating were tohave a Tg dissimilar to that of PET, it would be difficult, if notimpossible, to choose a blowing temperature suitable for both materials.When the barrier coating materials have a Tg similar to PET, the coatedpreform behaves during blow molding as if it were made of one material,expanding smoothly and creating a cosmetically appealing container withan even thickness and uniform coating of the barrier material where itis applied.

[0105] The glass transition temperature of PET occurs in a window ofabout 75-85° C., depending upon how the PET has been processedpreviously. The Tg for preferred barrier materials of embodiments of thepresent invention is preferably 55 to 140° C., more preferably 90 to110° C.

[0106] Another factor which has an impact on the performance of barrierpreforms during blow molding is the state of the material. The preferredbarrier materials of preferred embodiments of the present invention areamorphous rather than crystalline. This is because materials in anamorphous state are easier to form into bottles and containers by use ofa blow molding process than materials in a crystalline state. PET canexist in both crystalline and amorphous forms. However, in embodimentsof the present invention it is highly preferred that the crystallinityof the PET be minimized and the amorphous state maximized in order tocreate a semi-crystalline state which, among other things, aidsinterlayer adhesion and in the blow molding process. A PET articleformed from a melt of PET, as in injection molding, can be guided into asemi-crystalline form by cooling the melt at a high rate, fast enough toquench the crystallization process, freezing the PET in a mostlyamorphous state. Additionally, use of “high IPA PET” as describedearlier herein will allow easier quenching of the crystallizationprocess because it crystallizes at a lower rate than homopolymer PET.

[0107] Intrinsic viscosity and melt index are two properties which arerelated to a polymer's molecular weight. These properties give anindication as to how materials will act under various processingconditions, such as injection molding and blow molding processes.

[0108] Barrier materials for use in the articles and methods of thepresent invention have an intrinsic viscosity of preferably 0.70-0.90dl/g, more preferably 0.74-0.87 dl/g, most preferably 0.84-0.85 dl/g anda melt index of preferably 5-30, more preferably 7-12, most preferably10.

[0109] Barrier materials of embodiments of the present inventionpreferably have tensile strength and creep resistance similar to PET.Similarity in these physical properties allows the barrier coating toact as more than simply a gas barrier. A barrier coating having physicalproperties similar to PET acts as a structural component of thecontainer, allowing the barrier material to displace some of thepolyethylene terephthalate in the container without sacrificingcontainer performance. Displacement of PET allows for the resultingbarrier-coated containers to have physical performance andcharacteristics similar to their uncoated counterparts without asubstantial change in weight or size. It also allows for any additionalcost from adding the barrier material to be defrayed by a reduction inthe cost per container attributed to PET.

[0110] Similarity in tensile strength between PET and the barriercoating materials helps the container to have structural integrity. Thisis especially important if some PET is displaced by barrier material.Barrier-coated bottles and containers having features in accordance withthe present invention are able to withstand the same physical forces asan uncoated container, allowing, for example, barrier-coated containersto be shipped and handled in the customary manner of handling uncoatedPET containers. If the barrier-coating material were to have a tensilestrength substantially lower than that of PET, a container having somePET displaced by barrier material would likely not be able to withstandthe same forces as an uncoated container.

[0111] Similarity in creep resistance between PET and the barriercoating materials helps the container to retain its shape. Creepresistance relates to the ability of a material to resist changing itsshape in response to an applied force. For example, a bottle which holdsa carbonated liquid needs to be able to resist the pressure of dissolvedgas pushing outward and retain its original shape. If the barriercoating material were to have a substantially lower resistance to creepthan PET in a container, the resulting container would be more likely todeform over time, reducing the shelf-life of the product.

[0112] For applications where optical clarity is of importance,preferred barrier materials have an index of refraction similar to thatof PET. When the refractive index of the PET and the barrier coatingmaterial are similar, the preforms and, perhaps more importantly, thecontainers blown therefrom are optically clear and, thus, cosmeticallyappealing for use as a beverage container where clarity of the bottle isfrequently desired. If, however, the two materials have substantiallydissimilar refractive indices when they are placed in contact with eachother, the resulting combination will have visual distortions and may becloudy or opaque, depending upon the degree of difference in therefractive indices of the materials.

[0113] Polyethylene terephthalate has an index of refraction for visiblelight within the range of about 1.40 to 1.75, depending upon itsphysical configuration. When made into preforms, the refractive index ispreferably within the range of about 1.55 to 1.75, and more preferablyin the range of 1.55-1.65. After the preform is made into a bottle, thewall of the final product, may be characterized as a biaxially-orientedfilm since it is subject to both hoop and axial stresses in the blowmolding operation. Blow molded PET generally exhibits a refractive indexwithin the range of about 1.40 to 1.75, usually about 1.55 to 1.75,depending upon the stretch ratio involved in the blow molding operation.For relatively low stretch ratios of about 6:1, the refractive indexwill be near the lower end, whereas for high stretch ratios, about 10:1,the refractive index will be near the upper end of the aforementionedrange. It will be recognized that the stretch ratios referred to hereinare biaxial stretch ratios resulting from and include the product of thehoop stretch ratio and the axial stretch ratio. For example, in a blowmolding operation in which the final preform is enlarged by a factor of2.5 in the axial direction and a factor of 3.5 diametrically, thestretch ratio will be about 8.75 (2.5×3.5).

[0114] Using the designation n_(i) to indicate the refractive index forPET and n_(o) to indicate the refractive index for the barrier material,the ratio between the values n_(i) and n_(o) is preferably 0.8-1.3, morepreferably 1.0-1.2, most preferably 1.0-1.1. As will be recognized bythose skilled in the art, for the ratio n_(i)/n_(o)−1 the distortion dueto refractive index will be at a minimum, because the two indices areidentical. As the ratio progressively varies from one, however, thedistortion increases progressively.

D. Preferred Barrier Coating Materials and Their Preparation

[0115] The preferred barrier coating materials for use in the articlesand methods of the present invention include Phenoxy-type Thermoplasticmaterials, copolyesters of terephthalic acid, isophthalic acid, and atleast one diol having good barrier properties as compared to PET(Copolyester Barrier Materials), Polyamides, PEN, PEN copolymers,PEN/PET blends, and combinations thereof. Preferably, the Phenoxy-typeThermoplastics used as barrier materials in the present invention areone of the following types:

[0116] (1) hydroxy-functional poly(amide ethers) having repeating unitsrepresented by any one of the Formulae Ia, Ib or Ic:

[0117] (2) poly(hydroxy amide ethers) having repeating units representedindependently by any one of the Formulae IIa, IIb or IIc:

[0118] (3) amide- and hydroxymethyl-functionalized polyethers havingrepeating units represented by Formula III:

[0119] (4) hydroxy-functional polyethers having repeating unitsrepresented by Formula IV:

[0120] (5) hydroxy-functional poly(ether sulfonamides) having repeatingunits represented by Formulae Va or Vb:

[0121] (6) poly(hydroxy ester ethers) having repeating units representedby Formula VI:

[0122] (7) hydroxy-phenoxyether polymers having repeating unitsrepresented by Formula VII:

[0123] and

[0124] (8) poly(hydroxyamino ethers) having repeating units representedby Formula VIII:

[0125] wherein each Ar individually represents a divalent aromaticmoiety, substituted divalent aromatic moiety or heteroaromatic moiety,or a combination of different divalent aromatic moieties, substitutedaromatic moieties or heteroaromatic moieties; R is individually hydrogenor a monovalent hydrocarbyl moiety; each Ar₁ is a divalent aromaticmoiety or combination of divalent aromatic moieties bearing amide orhydroxymethyl groups; each Ar₂ is the same or different than Ar and isindividually a divalent aromatic moiety, substituted aromatic moiety orheteroaromatic moiety or a combination of different divalent aromaticmoieties, substituted aromatic moieties or heteroaromatic moieties; R₁is individually a predominantly hydrocarbylene moiety, such as adivalent aromatic moiety, substituted divalent aromatic moiety, divalentheteroaromatic moiety, divalent alkylene moiety, divalent substitutedalkylene moiety or divalent heteroalkylene moiety or a combination ofsuch moieties; R₂ is individually a monovalent hydrocarbyl moiety; A isan amine moiety or a combination of different amine moieties; X is anamine, an arylenedioxy, an arylenedisulfonamido or an arylenedicarboxymoiety or combination of such moieties; and Ar₃ is a “cardo” moietyrepresented by any one of the Formulae:

[0126] wherein Y is nil, a covalent bond, or a linking group, whereinsuitable linking groups include, for example, an oxygen atom, a sulfuratom, a carbonyl atom, a sulfonyl group, or a methylene group or similarlinkage; n is an integer from about 10 to about 1000; x is 0.01 to 1.0;and y is 0 to 0.5.

[0127] The term “predominantly hydrocarbylene” means a divalent radicalthat is predominantly hydrocarbon, but which optionally contains a smallquantity of a heteroatomic moiety such as oxygen, sulfur, imino,sulfonyl, sulfoxyl, and the like.

[0128] The hydroxy-functional poly(amide ethers) represented by FormulaI are preferably prepared by contacting anN,N′-bis(hydroxyphenylamido)alkane or arene with a diglycidyl ether asdescribed in U.S. Pat. Nos. 5,089,588 and 5,143,998.

[0129] The poly(hydroxy amide ethers) represented by Formula II areprepared by contacting a bis(hydroxyphenylamido)alkane or arene, or acombination of 2 or more of these compounds, such asN,N′-bis(3-hydroxyphenyl) adipamide orN,N′-bis(3-hydroxyphenyl)glutaramide, with an epihalohydrin as describedin U.S. Pat. No. 5,134,218.

[0130] The amide- and hydroxymethyl-functionalized polyethersrepresented by Formula III can be prepared, for example, by reacting thediglycidyl ethers, such as the diglycidyl ether of bisphenol A, with adihydric phenol having pendant amido, N-substituted amido and/orhydroxyalkyl moieties, such as 2,2-bis(4-hydroxyphenyl)acetamide and3,5-dihydroxybenzamide. These polyethers and their preparation aredescribed in U.S. Pat. Nos. 5,115,075 and 5,218,075.

[0131] The hydroxy-functional polyethers represented by Formula IV canbe prepared, for example, by allowing a diglycidyl ether or combinationof diglycidyl ethers to react with a dihydric phenol or a combination ofdihydric phenols using the process described in U.S. Pat. No. 5,164,472.Alternatively, the hydroxy-functional polyethers are obtained byallowing a dihydric phenol or combination of dihydric phenols to reactwith an epihalohydrin by the process described by Reinking, Barnabeo andHale in the Journal of Applied Polymer Science, Vol. 7, p. 2135 (1963).

[0132] The hydroxy-functional poly(ether sulfonamides) represented byFormula V are prepared, for example, by polymerizing an N,N′-dialkyl orN,N′-diaryldisulfonamide with a diglycidyl ether as described in U.S.Pat. No. 5,149,768.

[0133] The poly(hydroxy ester ethers) represented by Formula VI areprepared by reacting diglycidyl ethers of aliphatic or aromatic diacids,such as diglycidyl terephthalate, or diglycidyl ethers of dihydricphenols with, aliphatic or aromatic diacids such as adipic acid orisophthalic acid. These polyesters are described in U.S. Pat. No.5,171,820.

[0134] The hydroxy-phenoxyether polymers represented by Formula VII areprepared, for example, by contacting at least one dinucleophilic monomerwith at least one diglycidyl ether of a cardo bisphenol, such as9,9-bis(4-hydroxyphenyl)fluorene, phenolphthalein, orphenolphthalimidine or a substituted cardo bisphenol, such as asubstituted bis(hydroxyphenyl)fluorene, a substituted phenolphthalein ora substituted phenolphthalimidine under conditions sufficient to causethe nucleophilic moieties of the dinucleophilic monomer to react withepoxy moieties to form a polymer backbone containing pendant hydroxymoieties and ether, imino, amino, sulfonamido or ester linkages. Thesehydroxy-phenoxyether polymers are described in U.S. Pat. No. 5,184,373.

[0135] The poly(hydroxyamino ethers) (“PHAE” or polyetheramines)represented by Formula VIII are prepared by contacting one or more ofthe diglycidyl ethers of a dihydric phenol with an amine having twoamine hydrogens under conditions sufficient to cause the amine moietiesto react with epoxy moieties to form a polymer backbone having aminelinkages, ether linkages and pendant hydroxyl moieties. These compoundsare described in U.S. Pat. No. 5,275,853.

[0136] Phenoxy-type Thermoplastics of Formulae I-VIII may be acquiredfrom Dow Chemical Company (Midland, Mich. U.S.A.).

[0137] The Phenoxy-type Thermoplastics commercially available fromPhenoxy Associates, Inc. are suitable for use in the present invention.These hydroxy-phenoxyether polymers are the condensation reactionproducts of a dihydric polynuclear phenol, such as bisphenol A, and anepihalohydrin and have the repeating units represented by Formula IVwherein Ar is an isopropylidene diphenylene moiety. The process forpreparing these is described in U.S. Pat. No. 3,305,528, incorporatedherein by reference in its entirety.

[0138] The most preferred Phenoxy-type Thermoplastics are thepoly(hydroxyamino ethers) (“PHAE”) represented by Formula VIII. Anexample is that sold as XU19040.00L by Dow Chemical Company.

[0139] Examples of preferred Copolyester Barrier Materials and a processfor their preparation is described in U.S. Pat. No. 4,578,295 toJabarin. They are generally prepared by heating a mixture of at leastone reactant selected from isophthalic acid, terephthalic acid and theirC₁ to C₄ alkyl esters with 1,3 bis(2-hydroxyethoxy)benzene and ethyleneglycol. Optionally, the mixture may further comprise one or moreester-forming dihydroxy hydrocarbon and/orbis(4-β-hydroxyethoxyphenyl)sulfone. Especially preferred CopolyesterBarrier Materials are available from Mitsui Petrochemical Ind. Ltd.(Japan) as B-010, B-030 and others of this family.

[0140] Examples of preferred Polyamide barrier materials include MXD-6from Mitsubishi Gas Chemical (Japan). Other preferred Polyamide barriermaterials are polyamides containing preferably 1-10% polyester, morepreferably 1-2% polyester by weight, where the polyester is preferablyPET, more preferably high IPA PET. These materials are made by addingthe polyester to the polyamide polycondensation mixture. “Polyamide” asused herein shall include those polyamides containing PET or otherpolyesters.

[0141] Other preferred barrier materials include polyethylenenaphthalate (PEN), PEN copolyester, and PET/PEN blends. PEN materialscan be purchased from Shell Chemical Company.

E. Preparation of Polyesters

[0142] Polyesters and methods for their preparation (including thespecific monomers employed in their formation, their proportions,polymerization temperatures, catalysts and other conditions) arewell-known in the art and reference is made thereto for the purposes ofthis invention. For purposes of illustration and not limitation,reference is particularly made to pages 1-62 of Volume 12 of theEncyclopedia of Polymer Science and Engineering, 1988 revision, JohnWiley & Sons.

[0143] Typically, polyesters are derived from the reaction of a di- orpolycarboxylic acid with a di- or polyhydric alcohol. Suitable di- orpolycarboxylic acids include polycarboxylic acids and the esters andanthydrides of such acids, and mixture thereof. Representativecarboxylic acids include phthalic, isophthalic, adipic azelaic,terephthalic, oxalic, malonic, succinic, glutaric, sebacic, and thelike. Dicarboxylic components are preferred. Terephthalic acid is mostcommonly employed and preferred in the preparation of polyester films.α, β-Unsaturated di- and polycarboxylic acids (including esters oranthydrides of such acids and mixtures thereof) can be used as partialreplacement for the saturated carboxylic components. Representativeα,β-unsaturated di- and polycarboxylic acids include maleic, fumaric,aconitic, itaconic, mesaconic, citraconic, monochloromaleic and thelike.

[0144] Typical di- and polyhydric alcohols used to prepare the polyesterare those alcohols having at least two hydroxy groups, although minoramounts of alcohol having more or less hydroxy groups may be used.Dihydroxy alcohols are preferred. Dihydroxy alcohols conventionallyemployed in the preparation of polyesters include diethylene glycol;dipropylene glycol; ethylene glycol; 1,2-propylene glycol;1,4-butanediol; 1,4-pentanediol; 1,5-hexanediol,1,4-cyclohexanedimethanol and the like with 1,2-propylene glycol beingpreferred. Mixtures of the alcohols can also be employed. The di- orpolyhydric alcohol component of the polyester is usually stoichiometricor in slight excess with respect to the acid. The excess of the di- orpolyhydric alcohol will seldom exceed about 20 to 25 mole percent andusually is between about 2 and about 10 mole percent.

[0145] The polyester is generally prepared by heating a mixture of thedi- or polyhydric alcohol and the di- or polycarboxylic component intheir proper molar ratios at elevated temperatures, usually betweenabout 100° C. and 250° C. for extended periods of time, generallyranging from 5 to 15 hours. Polymerization inhibitors such ast-butylcatechol may advantageously be used.

[0146] PET, the preferred polyester, which is commonly made bycondensation of terephthalic acid and ethylene glycol, may be purchasedfrom Dow Chemical Company (Midland, Mich.), and Allied Signal Inc.(Baton Rouge, La.), among many others.

[0147] Preferably, the PET used is that in which isophthalic acid (IPA)is added during the manufacture of the PET to form a copolymer. Theamount of IPA added is preferably 2-10% by weight, more preferably 3-8%by weight, most preferably 4-5% by weight. The most preferred range isbased upon current FDA regulations which currently do not allow for PETmaterials having an IPA content of more than 5% to be in contact withfood or drink. High-IPA PET (PET having more than about 2% IPA byweight) can be made as discussed above, or purchased from a number ofdifferent manufacturers, for instance PET with 4.8% IPA may be purchasedfrom SKF (Italy) and 10% IPA PET may be purchased from INCA (DowEurope).

[0148] Additionally, if a Polyamide is chosen as the barrier material,it is preferred to use a polyamide-containing polyester. Suchpolyamide-containing polyesters are formed by adding polyamide to thepolyester polycondensation mixture. The amount of polyamide in thepolyester is preferably 1-10% by weight, more preferably 1-2% by weight.The polyester used is preferably PET, more preferably high IPA PET.

F. Materials to Enhance Barrier Properties of Barrier Resins

[0149] The barrier materials disclosed above may be used in combinationwith other materials which enhance the barrier properties. Generallyspeaking, one cause for the diffusion of gases through a material is theexistence of gaps or holes in the material at the molecular levelthrough which the gas molecules can pass. The presence of intermolecularforces in a material, such as hydrogen bonding, allows for interchaincohesion in the matrix which closes these gaps and discourages diffusionof gases. One may also increase the gas-barrier ability of good barriermaterials by adding an additional molecule or substance which takesadvantage of such intermolecular forces and acts as a bridge betweenpolymer chains in the matrix, thus helping to close the holes in thematrix and reduce gas diffusion.

[0150] Derivatives of the diol resorcinol (m-dihydroxybenzene), whenreacted with other monomers in the manufacture of PHAE, PET, CopolyesterBarrier Materials, and other barrier materials, will generally result ina material which has better barrier properties than the same material ifit does not contain the resorcinol derivative. For example, resorcinoldiglycidyl ether can be used in PHAE and hydroxyethyl ether resorcinolcan be used in PET and other polyesters and Copolyester BarrierMaterials.

[0151] One measure of the efficacy of a barrier is the effect that ithas upon the shelf life of the material. The shelf life of a carbonatedsoft drink in a 32 oz PET non-barrier bottle is approximately 12-16weeks. Shelf life is determined as the time at which less than 85% ofthe original amount of carbon dioxide is remaining in the bottle.Bottles coated with PHAE using the inject-over-inject method describedbelow have been found to have a shelf life 2 to 3 times greater thanthat of PET alone. If, however, PHAE with resorcinol diglycidyl ether isused, the shelf life can be increased to 4 to 5 times that of PET alone.

[0152] Another way of enhancing the barrier properties of a material isto add a substance which “plugs” the holes in the polymer matrix andthus discourages gases from passing through the matrix. Alternatively, asubstance may aid in creating a more tortuous path for gas molecules totake as they permeate a material. One such substance, referred to hereinby the term “Nanoparticles” or “nanoparticular material” are tinyparticles of materials which enhance the barrier properties of amaterial by creating a more tortuous path for migrating oxygen or carbondioxide. One preferred type of nanoparticular material is amicroparticular clay-based product available from Southern ClayProducts.

G. Preparing Barrier-Coated Articles

[0153] Once a suitable barrier coating material is chosen, the coatedpreform must be made in a manner that promotes adhesion between the twomaterials. Generally, adherence between the barrier coating materialsand PET increases as the surface temperature of the PET increases.Therefore, it is preferable to perform coating on heated preforms,although the preferred barrier materials will adhere to PET at roomtemperature.

[0154] There are a number of methods of producing a coated PET preformin accordance with the present invention. Preferred methods include dipcoating, spray coating, flame spraying fluidized bed dipping, andelectrostatic powder spraying. Another preferred method, lamellarinjection molding, is discussed in more detail below. Each of the abovemethods is introduced and described in my copending U.S. applicationSer. No. 09/147,971, which was filed on Oct. 19, 1998, entitledBARRIER-COATED POLYESTER, which is hereby incorporated by reference inits entirety.

[0155] An especially preferred method of producing a coated PET preformis referred to herein generally as overmolding, and sometimes asinject-over-inject (“IOI”). The name refers to a procedure which usesinjection molding to inject one or more layers of barrier material overan existing preform, which preferably was itself made by injectionmolding. The terms “overinjecting” and “overmolding” are used herein todescribe the coating process whereby a layer of material, preferablycomprising barrier material, is injected over an existing preform. In anespecially preferred embodiment, the overinjecting process is performedwhile the underlying preform has not yet fully cooled. Overinjecting maybe used to place one or more additional layers of materials such asthose comprising barrier material, recycled PET, or other materials overa coated or uncoated preform.

[0156] The overmolding is carried out by using an injection moldingprocess using equipment similar to that used to form the uncoatedpreform itself. A preferred mold for overmolding, with an uncoatedpreform in place is shown in FIG. 9. The mold comprises two halves, acavity half 92 and a mandrel half 94, and is shown in FIG. 9 in theclosed position prior to overinjecting. The cavity half 92 comprises acavity in which the uncoated preform is placed. The support ring 38 ofthe preform rests on a ledge 96 and is held in place by the mandrel half94, which exerts pressure on the support ring 38, thus sealing the neckportion off from the body portion of the preform. The cavity half 92 hasa plurality of tubes or channels 104 therein which carry a fluid.Preferably the fluid in the channels circulates in a path in which thefluid passes into an input in the cavity half 92, through the channels104, out of the cavity half 92 through an output, through a chiller orother cooling device, and then back into the input. The circulatingfluid serves to cool the mold, which in turn cools the plastic meltwhich is injected into the mold to form the coated preform.

[0157] The mandrel half 94 of the mold comprises a mandrel 98. Themandrel 98, sometimes called a core, protrudes from the mandrel half 94of the mold and occupies the central cavity of the preform. In additionto helping to center the preform in the mold, the mandrel 98 cools theinterior of the preform. The cooling is done by fluid circulatingthrough channels 106 in the mandrel half 94 of the mold, mostimportantly through the length of the mandrel 98 itself. The channels106 of the mandrel half 94 work in a manner similar to the channels 104in the cavity half 92, in that they create the portion of the paththrough which the cooling fluid travels which lies in the interior ofthe mold half.

[0158] As the preform sits in the mold cavity, the body portion of thepreform is centered within the cavity and is completely surrounded by avoid space 100. The preform, thus positioned, acts as an interior diemandrel in the subsequent injection procedure. The melt of theovermolding material, preferably comprising a barrier material, is thenintroduced into the mold cavity from the injector via gate 102 and flowsaround the preform, preferably surrounding at least the body portion 34of the preform. Following overinjection, the overmolded layer will takethe approximate size and shape of the void space 100.

[0159] To carry out the overmolding procedure, one preferably heats theinitial preform which is to be coated preferably to a temperature aboveits Tg. In the case of PET, that temperature is preferably 100 to 200°C., more preferably 180-225° C. If a temperature at or above thetemperature of crystallization for PET is used, which is about 120° C.,care should be taken when cooling the PET in the preform. The coolingshould be sufficient to minimize crystallization of the PET in thepreform so that the PET is in the preferred semi-crystalline state.Alternatively, the initial preform used may be one which has been veryrecently injection molded and not fully cooled, as to be at an elevatedtemperature as is preferred for the overmolding process.

[0160] The coating material is heated to form a melt of a viscositycompatible with use in an injection molding apparatus. The temperaturefor this, the inject temperature, will differ among materials, asmelting ranges in polymers and viscosities of melts may vary due to thehistory, chemical character, molecular weight, degree of branching andother characteristics of a material. For the preferred barrier materialsdisclosed above, the inject temperature is preferably in the range ofabout 160-325° C., more preferably 200 to 275° C. For example, for theCopolyester Barrier Material B-010, the preferred temperature is around210° C., whereas for the PHAE XU-19040.00L the preferred temperature isin the range of 160-260° C., and is more preferably about 200-280° C.Most preferably, the PHAE inject temperature is about 190-230° C. Ifrecycled PET is used, the inject temperature is preferably 250-300° C.The coating material is then injected into the mold in a volumesufficient to fill the void space 100. If the coating material comprisesbarrier material, the coating layer is a barrier layer.

[0161] The coated preform is preferably cooled at least to the pointwhere it can be displaced from the mold or handled without beingdamaged, and removed from the mold where further cooling may take place.If PET is used, and the preform has been heated to a temperature near orabove the temperature of crystallization for PET, the cooling should befairly rapid and sufficient to ensure that the PET is primarily in thesemi-crystalline state when the preform is fully cooled. As a result ofthis process, a strong and effective bonding takes place between theinitial preform and the subsequently applied coating material.

[0162] Overmolding can be also used to create coated preforms with threeor more layers. In FIG. 16, there is shown a three-layer embodiment of apreform 132 in accordance with the present invention. The preform showntherein has two coating layers, a middle layer 134 and an outer layer134. The relative thickness of the layers shown in FIG. 16 may be variedto suit a particular combination of layer materials or to allow for themaking of different sized bottles. As will be understood by one skilledin the art, a procedure analogous to that disclosed above would befollowed, except that the initial preform would be one which had alreadybeen coated, as by one of the methods for making coated preformsdescribed herein, including overmolding.

[0163] 1. First Preferred Method and Apparatus for Overmolding

[0164] A first preferred apparatus for performing the overmoldingprocess is based upon the use of a 330-330-200 machine by Engel(Austria). The preferred mold portion the machine is shown schematicallyin FIGS. 10-15 and comprises a movable half 142 and a stationary half144. Both halves are preferably made from hard metal. The stationaryhalf 144 comprises at least two mold sections 146, 148, wherein eachmold section comprises N (N>0) identical mold cavities 114, 120, aninput and output for cooling fluid, channels allowing for circulation ofcooling fluid within the mold section, injection apparatus, and hotrunners channeling the molten material from the injection apparatus tothe gate of each mold cavity. Because each mold section forms a distinctpreform layer, and each preform layer is preferably made of a differentmaterial, each mold section is separately controlled to accommodate thepotentially different conditions required for each material and layer.The injector associated with a particular mold section injects a moltenmaterial, at a temperature suitable for that particular material,through that mold section's hot runners and gates and into the moldcavities. The mold section's own input and output for cooling fluidallow for changing the temperature of the mold section to accommodatethe characteristics of the particular material injected into a moldsection. Consequently, each mold section may have a different injectiontemperature, mold temperature, pressure, injection volume, cooling fluidtemperature, etc. to accommodate the material and operationalrequirements of a particular preform layer.

[0165] The movable half 142 of the mold comprises a turntable 130 and aplurality of cores or mandrels 98. The alignment pins guide the movablehalf 142 to slidably move in a preferably horizontal direction towardsor away from the stationary half 144. The turntable 130 may rotate ineither a clockwise or counterclockwise direction, and is mounted ontothe movable half 142. The plurality of mandrels 98 are affixed onto theturntable 130. These mandrels 98 serve as the mold form for the interiorof the preform, as well as serving as a carrier and cooling device forthe preform during the molding operation. The cooling system in themandrels is separate from the cooling system in the mold sections.

[0166] The mold temperature or cooling for the mold is controlled bycirculating fluid. There is separate cooling fluid circulation for themovable half 142 and for each of the mold sections 146, 148 of thestationary half 144. Therefore, in a mold having two mold sections inthe stationary half 144, there is separate cooling for each of the twomold sections plus separate cooling for the movable half 142 of themold. Analogously, in a mold having three mold sections in thestationary half, there are four separate cooling fluid circulation setups: one for each mold section, for a total of three, plus one for themovable half 142. Each cooling fluid circulation set up works in asimilar manner. The fluid enters the mold, flows through a network ofchannels or tubes inside as discussed above for FIG. 9, and then exitsthrough an output. From the output, the fluid travels through a pump,which keeps the fluid flowing, and a chilling system to keep the fluidwithin the desired temperature range, before going back into the mold.

[0167] In a preferred embodiment, the mandrels and cavities areconstructed of a high heat transfer material, such a beryllium, which iscoated with a hard metal, such as tin or chrome. The hard coating keepsthe beryllium from direct contact with the preform, as well as acting asa release for ejection and providing a hard surface for long life. Thehigh heat transfer material allows for more efficient cooling, and thusassists in achieving lower cycle times. The high heat transfer materialmay be disposed over the entire area of each mandrel and/or cavity, orit may be only on portions thereof. Preferably at least the tips of themandrels comprise high heat transfer material. Another, even morepreferred high heat transfer material is Ampcoloy, which is commerciallyavailable from Uudenholm, Inc.

[0168] The number of mandrels is equal to the total number of cavities,and the arrangement of the mandrels 98 on the movable half 142 mirrorsthe arrangement of the cavities 114, 120 on the stationary half 144. Toclose the mold, the movable half 142 moves towards the stationary half144, mating the mandrels 98 with the cavities 114, 120. To open themold, the movable half 142 moves away from the stationary half 144 suchthat the mandrels 98 are well clear of the block on the stationary half144. After the mandrels are fully withdrawn 98 from the mold sections146, 148, the turntable 130 of the movable half 142 rotates the mandrels98 into alignment with a different mold section. Thus, the movable halfrotates 360°/(number of mold sections in the stationary half) degreesafter each withdrawal of the mandrels from the stationary half. When themachine is in operation, during the withdrawal and rotation steps, therewill be preforms present on some or all of the mandrels.

[0169] The size of the cavities in a given mold section 146, 148 will beidentical; however the size of the cavities will differ among the moldsections. The cavities in which the uncoated preforms are first molded,the preform molding cavities 114, are smallest in size. The size of thecavities 120 in the mold section 148 in which the first coating step isperformed are larger than the preform molding cavities 114, in order toaccommodate the uncoated preform and still provide space for the coatingmaterial to be injected to form the overmolded coating. The cavities ineach subsequent mold section wherein additional overmolding steps areperformed will be increasingly larger in size to accommodate the preformas it gets larger with each coating step.

[0170] After a set of preforms has been molded and overmolded tocompletion, a series of ejectors eject the finished preforms off of themandrels 98. The ejectors for the mandrels operate independently, or atleast there is a single ejector for a set of mandrels equal in numberand configuration to a single mold section, so that only the completedpreforms are ejected. Uncoated or incompletely-coated preforms remain onthe mandrels so that they may continue in the cycle to the next moldsection. The ejection may cause the preforms to completely separate fromthe mandrels and fall into a bin or onto a conveyor. Alternatively, thepreforms may remain on the mandrels after ejection, after which arobotic arm or other such apparatus grasps a preform or group ofpreforms for removal to a bin, conveyor, or other desired location.

[0171]FIGS. 10 and 11 illustrate a schematic for an embodiment of theapparatus described above. FIG. 11 is the stationary half 144 of themold. In this embodiment, the block 124 has two mold sections, onesection 146 comprising a set of three preform molding cavities 114 andthe other section 148 comprising a set of three preform coating cavities120. Each of the preform coating cavities 120 is preferably like thatshown in FIG. 9, discussed above. Each of the preform molding cavities114 is preferably similar to that shown in FIG. 9, in that the materialis injected into a space defined by the mandrel 98 (albeit without apreform already thereon) and the wall of the mold which is cooled byfluid circulating through channels inside the mold block. Consequently,one full production cycle of this apparatus will yield three two-layerpreforms. If more than three preforms per cycle is desired, thestationary half can be reconfigured to accommodate more cavities in eachof the mold sections. An example of this is seen in FIG. 13, whereinthere is shown a stationary half of a mold comprising two mold sections,one 146 comprising forty-eight preform molding cavities 114 and theother 148 comprising forty-eight preform coating cavities 120. If athree or more layer preform is desired, the stationary half 144 can bereconfigured to accommodate additional mold sections, one for eachpreform layer

[0172]FIG. 10 illustrates the movable half 142 of the mold. The movablehalf comprises six identical mandrels 98 mounted on the turntable 130.Each mandrel 98 corresponds to a cavity on the stationary half 144 ofthe mold. The movable half also comprises alignment pegs 110, whichcorrespond to the receptacles 112 on the stationary half 144. When themovable half 142 of the mold moves to close the mold, the alignment pegs110 are mated with their corresponding receptacles 112 such that themolding cavities 114 and the coating cavities 120 align with themandrels 98. After alignment and closure, half of the mandrels 98 arecentered within preform molding cavities 114 and the other half of themandrels 98 are centered within preform coating cavities 120.

[0173] The configuration of the cavities, mandrels, and alignment pegsand receptacles must all have sufficient symmetry such that after themold is separated and rotated the proper number of degrees, all of themandrels line up with cavities and all alignment pegs line up withreceptacles. Moreover, each mandrel must be in a cavity in a differentmold section than it was in prior to rotation in order to achieve theorderly process of molding and overmolding in an identical fashion foreach preform made in the machine.

[0174] Two views of the two mold halves together are shown in FIGS. 14and 15. In FIG. 14, the movable half 142 is moving towards thestationary half 144, as indicated by the arrow. Two mandrels 98, mountedon the turntable 130, are beginning to enter cavities, one enters amolding cavity 114 and the other is entering a coating cavity 120mounted in the block 124. In FIG. 15, the mandrels 98 are fullywithdrawn from the cavities on the stationary side. The preform moldingcavity 114 has cooling circulation which is separate from the coolingcirculation for the preform coating cavity 120, which comprises theother mold section 148. The two mandrels 98 are cooled by a singlesystem which links all the mandrels together. The arrow in FIG. 15 showsthe rotation of the turntable 130. The turntable 130 could also rotateclockwise. Not shown are coated and uncoated preforms which would be onthe mandrels if the machine were in operation. The alignment pegs andreceptacles have also been left out for the sake of clarity.

[0175] The operation of the overmolding apparatus will be discussed interms of the preferred two mold section apparatus for making a two-layerpreform. The mold is closed by moving the movable half 142 towards thestationary half 144 until they are in contact. A first injectionapparatus injects a melt of first material into the first mold section146, through the hot runners and into the preform molding cavities 114via their respective gates to form the uncoated preforms each of whichbecome the inner layer of a coated preform. The first material fills thevoid between the preform molding cavities 114 and the mandrels 98.Simultaneously, a second injection apparatus injects a melt of secondmaterial into the second mold section 148 of the stationary half 144,through the hot runners and into each preform coating cavity 120 viatheir respective gates, such that the second material fills the void(100 in FIG. 9) between the wall of the coating cavity 120 and theuncoated preform mounted on the mandrel 98 therein.

[0176] During this entire process, cooling fluid is circulating throughthe three separate areas, corresponding to the mold section 146 of thepreform molding cavities 114, mold section 148 of the preform coatingcavities 120, and the movable half 142 of the mold, respectively. Thus,the melts and preforms are being cooled in the center by the circulationin the movable half that goes through the interior of the mandrels, aswell as on the outside by the circulation in each of the cavities. Theoperating parameters of the cooling fluid in the first mold section 146containing preform molding cavities 114 are separately controlled fromthe operating parameters of the cooling fluid in the second mold section148 containing the coating cavities to account for the differentmaterial characteristics of the preform and the coating. These are inturn separate from those of the movable half of 142 the mold whichprovides constant cooling for the interior of the preform throughout thecycle, whether the mold is open or closed.

[0177] The movable half 142 then slides back to separate the two moldhalves and open the mold until all of the mandrels 98 having preformsthereon are completely withdrawn from the preform molding cavities 114and preform coating cavities 120. The ejectors eject the coated,finished preforms off of the mandrels 98 which were just removed fromthe preform coating cavities. As discussed above, the ejection may causethe preforms to completely separate from the mandrels and fall into abin or onto a conveyor, or if the preforms remain on the mandrels afterejection, a robotic arm or other apparatus may grasp a preform or groupof preforms for removal to a bin, conveyor, or other desired location.The turntable 130 then rotates 180° so that each mandrel 98 having anuncoated preform thereon is positioned over a preform coating cavity120, and each mandrel from which a coated preform was just ejected ispositioned over a preform molding cavity 114. Rotation of the turntable130 may occur as quickly as 0.3 seconds. Using the alignment pegs 110,the mold halves again align and close, and the first injector injectsthe first material into the preform molding cavity 114 while the secondinjector injects the barrier material into the preform coating cavity120.

[0178] A production cycle of closing the mold, injecting the melts,opening the mold, ejecting finished barrier preforms, rotating theturntable, and closing the mold is repeated, so that preforms arecontinuously being molded and overmolded.

[0179] When the apparatus first begins running, during the initialcycle, no preforms are yet in the preform coating cavities 120.Therefore, the operator should either prevent the second injector frominjecting the second material into the second mold section during thefirst injection, or allow the second material to be injected and ejectand then discard the resulting single layer preform comprised solely ofthe second material. After this start-up step, the operator may eithermanually control the operations or program the desired parameters suchthat the process is automatically controlled.

[0180] Two layer preforms may be made using the first preferredovermolding apparatus described above. In one preferred embodiment, thetwo layer preform comprises an inner layer comprising polyester and anouter layer comprising barrier material. In especially preferredembodiments, the inner layer comprises virgin PET. The descriptionhereunder is directed toward the especially preferred embodiments of twolayer preforms comprising an inner layer of virgin PET. The descriptionis directed toward describing the formation of a single set of coatedpreforms 60 of the type seen in FIG. 4, that is, following a set ofpreforms through the process of molding, overmolding and ejection,rather than describing the operation of the apparatus as a whole. Theprocess described is directed toward preforms having a total thicknessin the wall portion 66 of about 3 mm, comprising about 2 mm of virginPET and about 1 mm of barrier material. The thickness of the two layerswill vary in other portions of the preform 60, as shown in FIG. 4.

[0181] It will be apparent to one skilled in the art that some of theparameters detailed below will differ if other embodiments of preformsare used. For example, the amount of time which the mold stays closedwill vary depending upon the wall thickness of the preforms. However,given the disclosure below for this preferred embodiment and theremainder of the disclosure herein, one skilled in the art would be ableto determine appropriate parameters for other preform embodiments.

[0182] The apparatus described above is set up so that the injectorsupplying the mold section 146 containing the preform molding cavities114 is fed with virgin PET and that the injector supplying the moldsection 148 containing the preform coating cavities 120 is fed with abarrier material. Both mold halves are cooled by circulating fluid,preferably water, at a temperature of preferably 0-30° C., morepreferably 10-15° C.

[0183] The movable half 142 of the mold is moved so that the mold isclosed. A melt of virgin PET is injected through the back of the block124 and into each preform molding cavity 114 to form an uncoated preform30 which becomes the inner layer of the coated preform. The injectiontemperature of the PET melt is preferably 250 to 320° C., morepreferably 255 to 280° C. The mold is kept closed for preferably 3 to 10seconds, more preferably 4 to 6 seconds while the PET melt stream isinjected and then cooled by the coolant circulating in the mold. Duringthis time, surfaces of the preforms which are in contact with surfacesof preform molding cavities 114 or mandrels 98 begin to form a skinwhile the cores of the preforms remain molten and unsolidified.

[0184] The movable half 142 of the mold is then moved so that the twohalves of the mold are separated at or past the point where the newlymolded preforms, which remain on the mandrels 98, are clear of thestationary side 144 of the mold. The interior of the preforms, incontact with the mandrel 98, continues to cool. The cooling ispreferably done in a manner which rapidly removes heat so thatcrystallization of the PET is minimized so that the PET will be in asemi-crystalline state. The chilled water circulating through the mold,as described above, should be sufficient to accomplish this task.

[0185] While the inside of the preform is cooling, the temperature ofthe exterior surface of the preform begins to rise as it absorbs heatfrom the molten core of the preform. This heating begins to soften theskin on the exterior surface of the newly molded preform. Although theskin, which had been cooled while in the mold cavity 114, increases intemperature and begins to soften when removed from the cavity, thissoftening of the skin is the result of significant heat absorption fromthe molten core. Thus, the initial formation and later softening of theskin speeds the overall cooling of the molten preform and helps avoidcrystallization during cooling.

[0186] When the mandrels 98 are clear of the stationary side 144 of themold, the turntable 130 then rotates 180° so that each mandrel 98 havinga molded preform thereon is positioned over a preform coating cavity120. Thus positioned, each of the other mandrels 98 which do not havemolded preforms thereon, are each positioned over a preform moldingcavity 114. The mold is again closed. Preferably the time betweenremoval from the preform molding cavity 114 to insertion into thepreform coating cavity 120 is 1 to 10 seconds, and more preferably 1 to3 seconds.

[0187] When the molded preforms are first placed into preform coatingcavities 120, the exterior surfaces of the preforms are not in contactwith a mold surface. Thus, the exterior skin is still softened and hotas described above because the contact cooling is only from the mandrelinside. The high temperature of the exterior surface of the uncoatedpreform (which forms the inner layer of the coated preform) aids inpromoting adhesion between the PET and barrier layers in the finishedbarrier coated preform. It is postulated that the surfaces of thematerials are more reactive when hot, and thus chemical interactionsbetween the barrier material and the virgin PET will be enhanced by thehigh temperatures. Barrier material will coat and adhere to a preformwith a cold surface, and thus the operation may be performed using acold initial uncoated preform, but the adhesion is markedly better whenthe overmolding process is done at an elevated temperature, as occursimmediately following the molding of the uncoated preform.

[0188] A second injection operation then follows in which a melt of abarrier material, is injected into each preform coating cavity 120 tocoat the preforms. The temperature of the melt of barrier material ispreferably 160 to 300° C. The exact temperature range for any individualbarrier material is dependent upon the specific characteristics of thatbarrier material, but it is well within the abilities of one skilled inthe art to determine a suitable range by routine experimentation giventhe disclosure herein. For example, if the PHAE barrier materialXU19040.00L is used, the temperature of the melt (inject temperature) ispreferably 160 to 260° C., more preferably 200 to 240° C., and mostpreferably 220 to 230° C. If the Copolyester Barrier Material B-010 isused, the injection temperature is preferably 160 to 260° C., morepreferably 190 to 250° C. During the same time that this set of preformsare being overmolded with barrier material in the preform coatingcavities 120, another set of uncoated preforms is being molded in thepreform molding cavities 114 as described above.

[0189] The two halves of the mold are again separated preferably 3 to 10seconds, more preferably 4 to 6 seconds following the initiation of theinjection step. The preforms which have just been barrier coated in thepreform coating cavities 120, are ejected from the mandrels 98. Theuncoated preforms which were just molded in preform molding cavities 114remain on their mandrels 98. The turntable 130 is then rotated 180° sothat each mandrel having an uncoated preform thereon is positioned overa coating cavity 120 and each mandrel 98 from which a coated preform wasjust removed is positioned over a molding cavity 114.

[0190] The cycle of closing the mold, injecting the materials, openingthe mold, ejecting finished barrier preforms, rotating the turntable,and closing the mold is repeated, so that preforms are continuouslybeing molded and overmolded. Those of skill in the art will appreciatethat dry cycle time of the apparatus may increase the overall productioncycle time for molding a complete preform.

[0191] One of the many advantages of using the process disclosed hereinis that the cycle times for the process are similar to those for thestandard process to produce uncoated preforms; that is the molding andcoating of preforms by this process is done in a period of time similarto that required to make uncoated PET preforms of similar size bystandard methods currently used in preform production. Therefore, onecan make barrier coated PET preforms instead of uncoated PET preformswithout a significant change in production output and capacity.

[0192] If a PET melt cools slowly, the PET will take on a crystallineform. Because crystalline polymers do not blow mold as well as amorphouspolymers, a preform of crystalline PET would not be expected to performas well in forming containers according to the present invention. If,however, the PET is cooled at a rate faster than the crystal formationrate, as is described herein, crystallization will be minimized and thePET will take on a semi-crystalline form. The amorphous form is idealfor blow molding. Thus, sufficient cooling of the PET is crucial toforming preforms which will perform as needed when processed.

[0193] The rate at which a layer of PET cools in a mold such asdescribed herein is proportional to the thickness of the layer of PET,as well as the temperature of the cooling surfaces with which it is incontact. If the mold temperature factor is held constant, a thick layerof PET cools more slowly than a thin layer. This is because it takes alonger period of time for heat to transfer from the inner portion of athick PET layer to the outer surface of the PET which is in contact withthe cooling surfaces of the mold than it would for a thinner layer ofPET because of the greater distance the heat must travel in the thickerlayer. Thus, a preform having a thicker layer of PET needs to be incontact with the cooling surfaces of the mold for a longer time thandoes a preform having a thinner layer of PET. In other words, with allthings being equal, it takes longer to mold a preform having a thickwall of PET than it takes to mold a preform having a thin wall of PET.

[0194] The uncoated preforms of this invention, including those made bythe first injection in the above-described apparatus, are preferablythinner than a conventional PET preform for a given container size. Thisis because in making the barrier coated preforms, a quantity of the PETwhich would be in a conventional PET preform can be displaced by asimilar quantity of one of the preferred barrier materials. This can bedone because the preferred barrier materials have physical propertiessimilar to PET, as described above. Thus, when the barrier materialsdisplace an approximately equal quantity of PET in the walls of apreform or container, there will not be a significant difference in thephysical performance of the container. Because the preferred uncoatedpreforms which form the inner layer of the barrier coated preforms arethin-walled, they can be removed from the mold sooner than theirthicker-walled conventional counterparts. For example, the uncoatedpreform can be removed from the mold preferably after about 4-6 secondswithout crystallizing, as compared to about 12-24 seconds for aconventional PET preform having a total wall thickness of about 3 mm.All in all, the time to make a barrier coated preform is equal to orslightly greater (up to about 30%) than the time required to make amonolayer PET preform of this same total thickness.

[0195] Additionally, because the preferred barrier materials areamorphous, they will not require the same type of treatment as the PET.Thus, the cycle time for a molding-overmolding process as describedabove is generally dictated by the cooling time required by the PET. Inthe above-described method, barrier coated preforms can be made in aboutthe same time it takes to produce an uncoated conventional preform.

[0196] The advantage gained by a thinner preform can be taken a stepfarther if a preform made in the process is of the type in FIG. 4. Inthis embodiment of a coated preform, the PET wall thickness at 70 in thecenter of the area of the end cap 42 is reduced to preferably about ⅓ ofthe total wall thickness. Moving from the center of the end cap out tothe end of the radius of the end cap, the thickness gradually increasesto preferably about ⅔ of the total wall thickness, as at referencenumber 68 in the wall portion 66. The wall thickness may remain constantor it may, as depicted in FIG. 4, transition to a lower thickness priorto the support ring 38. The thickness of the various portions of thepreform may be varied, but in all cases, the PET and barrier layer wallthicknesses must remain above critical melt flow thickness for any givenpreform design.

[0197] Using preforms 60 of the design in FIG. 4 allows for even fastercycle times than that used to produce preforms 50 of the type in FIG. 3.As mentioned above, one of the biggest barriers to short cycle time isthe length of time that the PET needs to be cooled in the mold followinginjection. If a preform comprising PET has not sufficiently cooledbefore it is ejected from the mandrel, it will become substantiallycrystalline and potentially cause difficulties during blow molding.Furthermore, if the PET layer has not cooled enough before theovermolding process takes place, the force of the barrier materialentering the mold will wash away some of the PET near the gate area. Thepreform design in FIG. 4 takes care of both problems by making the PETlayer thinnest in the center of the end cap region 42, which is wherethe gate is in the mold. The thin gate section allows the gate area tocool more rapidly, so that the uncoated PET layer may be removed fromthe mold in a relatively short period of time while still avoidingcrystallization of the gate and washing of the PET during the secondinjection or overmolding phase.

[0198] The physical characteristics of the preferred barrier materialshelp to make this type of preform design workable. Because of thesimilarity in physical properties, containers having wall portions whichare primarily barrier material can be made without sacrificing theperformance of the container. If the barrier material used were notsimilar to PET, a container having a variable wall composition as inFIG. 4 would likely have weak spots or other defects that could affectcontainer performance.

[0199] 2. Second Preferred Method and Apparatus for Overmolding

[0200] A second preferred apparatus 150 for performing the overmoldingprocess is specially suited to accommodate the properties of thepreform's PET inner layer and barrier material outer layer. As discussedabove, the barrier material is generally amorphous and will cool to asemi-crystalline state regardless of the cooling rate. However, PET willcool to be substantially crystalline unless it is cooled very quickly.If, however, the PET is cooled quickly, crystallization will beminimized and the PET will be mostly amorphous and well suited for blowmolding. Since the inner layer of the preferred preform is formed of PETand the outer layer is formed of a barrier material, it is mostimportant to quickly cool the preform's inner layer in order to avoidcrystallization of the PET. Thus, this second preferred apparatusretains the completed preform on a cooling mandrel 98 for a time afterremoval from the mold coating cavity 158. Thus, the mandrel 98 continuesto extract heat from the inner layer of the preform while the preformmold cavities 156, 158 are available to form other preforms.

[0201]FIG. 17 shows the second embodiment of an apparatus 150 forovermolding. Hoppers 176, 178 feed injection machines 152, 154 whichheat the PET and barrier materials and provide melt streams injectedinto the preform molding cavity 156 and coating cavity 158,respectively. As in the first preferred embodiment discussed above, themold is divided into a stationary half 180 and a moveable half 182. Thestationary half 180 has at least two mold cavity sections 184, 186, eachcomprising at least one identical mold cavity. The first stationary moldsection 184 has at least one preform molding cavity 156 formed thereinand the second stationary mold section 186 has at least one preformcoating cavity 158 formed therein.

[0202] The mold of the present embodiment also has other aspects alreadydiscussed above. For instance, the mold cooling system has cooling tubeswith input and output ports for continuously circulating chilled coolantthrough the mold members; hot runners communicate molten plastic from aninjection apparatus into a void space between a mated mandrel and moldcavity to form a preform layer; the mold halves are constructed of hardmetal; and alignment pegs and corresponding receptacles aid alignment ofthe moveable half into the stationary half. Certain of these moldingcomponents are commercially available from Husky Injection MoldingSystems, Ltd.

[0203] With next reference to FIG. 18, the movable half 182 of the moldcomprises a turntable 160 divided into preferably four stations (A, B,C, D), each separated by 90° of rotation. In the illustrated embodiment,each station has a single mandrel 98 affixed thereto which correspondsto the single cavity formed in each stationary section 180. However, asin the first preferred embodiment discussed above, the number ofmandrels per station can be adjusted to increase the output of themachine so long as the number of cavities in each mold section isincreased correspondingly. Accordingly, although the illustratedembodiment shows only one mandrel per station, which would produce onlyone preform per station each production cycle, the apparatus could have,for example, three, eight, or even forty-eight mandrels per station andcavities per mold section.

[0204] Although all of the mandrels 98 are substantially identical, theywill be described and labeled herein as relating to the respectivestation on which they are located. Thus, the mandrel 98 disposed onstation A is labeled 98A, the mandrel disposed on station B is labeled98B, and so on. As above, the mandrels 98A-D serve as the mold form forthe interior of the preform. They also serve as a carrier and coolingsystem for the preform during the molding operation.

[0205] The present apparatus 150 is designed to use approximately thesame injection times, materials and temperatures discussed above.However, the orientation of the apparatus and the molds upon theturntable 160 are adapted to optimize both cooling of the preforms andoutput by the apparatus. A preferred method of using this apparatus toovermold a two layer preform, especially a two layer preform having abarrier material formed as the outer layer, is described below. Toillustrate the operation of this apparatus, molding of a preform will bedescribed by following station A through a complete production cycle. Itwill be appreciated that stations B-D also produce preforms concurrentlywith station A. FIG. 19 is a chart showing the relative activities ofeach of the stations at each point of the production cycle.

[0206] At the start of a cycle, the mandrel 96A on station A isunencumbered and directly aligned with the preform molding cavity 156 ofthe first section 184 of the stationary mold 182. An actuator 162,preferably hydraulic, lifts the turntable 130 so that the mandrel 98A isinserted into the molding cavity 156. The void space between the mandrel98A and the cavity 156 is then filled with a PET melt and allowed tocool in the mold for a short time, allowing the molded preform todevelop the cooling skin discussed previously. The turntable 130 is thenlowered, thus pulling the mandrel 98A out of the molding cavity 156. Thejust-injected preform remains on the mandrel 98A. Once the mandrels 98are cleared of the cavities, the turntable 130 is rotated 90° so thatthe mandrel 98A is directly aligned with the coating cavity 158 of thesecond stationary mold section 186. The rotary table 130 is againlifted, inserting the mandrel 98A and the associated preform into thecoating cavity 158. A melt of barrier material is injected to coat thepreform and is allowed to cool briefly. The table 130 is again loweredand the completely-injected molded preform remains on the mandrel 98A.The turntable is rotated 90°, however the mandrel 98A is no longeraligned with any mold cavity. Instead, the mandrel 98A is left in theopen and the cooling system within the mandrel 96A continues to cool thepreform quickly from the inner surface. Alternatively, the mandrel 98Amay also be aligned with a cooling system 163 having, for example, airor water cooling tubes 165 adapted to receive the mandrel 98A andaccompanying preform, cooling the preform from the outer surface.Meanwhile, mandrels 98B and 98C of stations B and C are interacting withthe coating and molding cavities 156, 158, respectively. When theinjections are complete, the turntable again rotates 90°. Again, themandrel 98A is not aligned with any mold cavity and the cooling processcontinues. Mandrels 98C and 98D of stations C and D are at this timeinteracting with the coating and molding cavities 156, 158,respectively. The cooling preform is next ejected from the mandrel 98Aby an ejector and is removed by a device such as a robot. The robot willdeposit the completed preform on a conveyor, bin or the like. With thepreform now ejected, the mandrel 98A is again unencumbered. Oncestations C and D have completed their interactions with the moldcavities, the turntable again rotates 90° and station A and mandrel 98Aare again aligned with the preform molding cavity 156. The cycle thusstarts over again.

[0207] The above apparatus 150 may be adapted to create an apparatus 170with improved versatility. With next reference to FIGS. 20 and 21,instead of the entire turntable 130 being raised and lowered by a singlehydraulic actuator, each station of the turntable 130 could be connectedto its own dedicated actuator 172. Thus, each of the stations canfunction independently to allow process optimization for the overmoldingoperation. For instance, depending on the material injected, it may bepreferable to cool the newly injected material in one cavity for alonger or shorter time than material injected into another cavity.Dedicated hydraulic actuators 172 allow the stations to be independentlymoved into and out of engagement with the respective mold cavity 156,158.

[0208] Although the above-described apparatus has been discussed in thecontext of forming a two-layer preform, it will be appreciated that thedisclosed principles of construction and operation may be adapted tomold preforms having numerous layers. For instance, additional stationscould be disposed on the turntable and additional injection machines andassociated coating cavities arranged on the machine to provide forinjections of additional layers.

[0209] 3. Third Preferred Method and Apparatus for Overmolding.

[0210] FIGS. 22-24 illustrate a third preferred method and apparatus 250for overmolding which uses the principle of retaining newly-injectedpreforms on the core to hasten cooling of the inner layer of thepreforms. While the preforms are thus cooling, other mandrels interactwith mold cavities to form further preforms. The cooled preform isejected from the mandrel on which it was formed just before the mandrelis reused to mold yet another preform.

[0211] The apparatus 250 includes a stationary first mold cavity 256connected by hot runners to an injection apparatus 252 which supplies aPET melt. A second injection apparatus 254 is adapted to supply a meltstream of a barrier material and is vertically and stationarily orientedadjacent the first cavity. A turntable 260 is mounted on a supportmember 264 slidably disposed on ways 266, allowing the turntable 260 andall parts associated therewith to travel horizontally back and forth onthe ways 266. The turntable 260 is rotatable through a vertical plane.Along the peripheral edges of the turntable are stations (AA, BB, CC,DD) similar to those discussed above. Mandrels 98AA-98DD are disposed onstations AA-DD, respectively. A second mold cavity 258 is disposed abovethe turntable 260 and is connected thereto. The mold cavity 258 ismovable by actuators 268 such as hydraulic cylinders or the like intoand out of engagement with a mandrel 98 disposed on the associatedstation. The second mold cavity 258 also moves horizontally with theturntable apparatus. The turntable stations and the mold cavities eachhave cooling systems, hot runner systems, alignment systems, and thelike as discussed above.

[0212]FIG. 22 shows the present apparatus 250 in an open position withnone of the molds engaged. FIG. 23 shows the apparatus 250 in a closedposition with the mandrels engaged with the respective cavities. Also,FIG. 23 shows the second mold cavity 258 in position to receive a meltstream from the second injection apparatus 254. To move from the openposition to the closed position, the second mold cavity 258 is firstdrawn towards the turntable 260 and into engagement with thecorresponding mandrel 98. The turntable assembly then moves horizontallyalong the ways to engage the first cavity 256 with the correspondingmandrel 98. When the engagement is complete, the second mold cavity 258is in communication with the second melt source 254.

[0213] A method of forming a two layer overmolded preform is describedbelow. As above, however, a particular mandrel 98AA will be followedthrough a production cycle. It will be appreciated that the othermandrels 98BB-DD are in concurrent use in other steps of the cycle. FIG.24 includes a chart showing the stages each station and mandrel willcomplete when forming a preform using this apparatus and showing therelative positions of each station during the production cycle.

[0214] At the beginning of a cycle, the apparatus is in the openposition and the mandrel 98AA is unencumbered by any preform. It isoriented so that it extends horizontally and is aligned with the firstmold cavity 256. Concurrently, mandrel 98DD, which has a single layerPET preform already disposed thereon, is oriented vertically and isaligned with the second mold cavity 258. To close the molds, the secondmold cavity 258 is first drawn into engagement with the mandrel 98DD andthe turntable assembly is moved horizontally along the ways 266 so thatthe mandrel 98AA engages the first mold cavity 256 and the secondinjector 254 is brought into communication with the second mold cavity258. The first injector 252 then injects a melt stream of PET into thefirst mold cavity 256 to fill the void space between the mandrel 98AAand the first mold cavity 256. Concurrently, the second injector 254injects a melt stream of barrier material into the void space betweenthe second mold cavity 258 and the PET layer disposed on the mandrel98DD. After a brief cooling time during which a skin is formed on thejust-injected PET preform, the turntable 260 is moved horizontally alongthe ways to pull the mandrel 98AA out of engagement with the firstcavity 256. As above, the just-injected preform remains on the mandrel98AA. The second mold cavity 258 is then withdrawn from the mandrel 98DDand the rotating turntable 260 is rotated 90° so that mandrel 98AA isnow aligned with the second mold cavity 258 and the mandrel 98BB is nowaligned with the first mold cavity 256. The mold is closed as above anda layer of barrier material is injected onto the PET preform on mandrel98AA while a PET preform is formed on mandrel 98BB. After a briefcooling time, the mold is again opened as above and the turntable 260 isrotated 90°. Mandrel 98AA is now free of any mold cavities and the newlymolded preform disposed on the mandrel 98AA is cooled during this time.Concurrently, mandrels 98BB and 98CC are in communication with the moldcavities. After the injections involving mandrels 98BB and 98CC arecomplete, the rotating table 260 is again rotated 90°. The mandrel 98AAis again retained in a cooling position out of alignment with any moldcavity. Concurrently, mandrels 98CC and 98DD engage the mold cavitiesand have layers injected thereon. The now-cooled preform is ejected fromthe mandrel 98AA to a conveyor or bin below the turntable 260 and theturntable 260 is again rotated 90°. Mandrel 98AA is again unencumbered,aligned with the first mold cavity 258, and ready to begin anotherproduction cycle.

[0215] Although the above-described apparatus 250 has been discussed inthe context of forming a two-layer preform, it will be appreciated thatthe disclosed principles of construction and operation may be adapted tomold preforms having numerous layers. For instance, additional stationscould be disposed on the turntable and additional injection machines andassociated coating cavities arranged on the machine to provide forinjections of additional layers.

[0216] 4. Lamellar Injection Molding

[0217] A barrier layer or a barrier preform can also be produced by aprocess called lamellar injection molding (LIM). The essence of LIMprocesses is the creation of a meltstream which is composed of aplurality of thin layers. In this application, it is preferred that theLIM meltstream is comprised of alternating thin layers of PET andbarrier material. The LIM process may be used in conjunction with theabove-described preferred overmolding apparatus to overmold a coating ofmultiple, thin layers.

[0218] One method of lamellar injection molding is carried out using asystem similar to that disclosed in several patents to Schrenk, U.S.Pat. Nos. 5,202,074, 5,540,878, and 5,628,950, the disclosures of whichare hereby incorporated in their entireties by reference, although theuse of that method as well as other methods obtaining similar lamellarmeltstreams are contemplated as part of the present invention. Referringto FIG. 25, a schematic of a LIM system 270 is shown. The system in FIG.25 shows a two material system, but it will be understood that a systemfor three or more materials could be used in a similar fashion. The twomaterials which are to form the layers, at least one of which ispreferably a barrier resin, are placed in separate hoppers 272 and 274,which feed two separate cylinders, 276 and 278 respectively. Thematerials are coextruded at rates designed to provide the desiredrelative amounts of each material to form a lamellar meltstreamcomprised of a layer from each cylinder.

[0219] The lamellar meltstream output from combined cylinders is thenapplied to a layer generation system 280. In the layer generation system280, the two layer meltstream is multiplied into a multi-layermeltstream by repetition of a series of actions much like one would doto make a pastry dough having a number of layers. First, one divides asection of meltstream into two pieces perpendicular to the interface ofthe two layers. Then the two pieces are flattened so that each of thetwo pieces is about as long as the original section before it was halvedin the first step, but only half as thick as the original section. Thenthe two pieces are recombined into one piece having similar dimensionsas the original section, but having four layers, by stacking one pieceon top of the other piece so that the sublayers of the two materials areparallel to each other. These three steps of dividing, flattening, andrecombining the meltstream may be done several times to create morethinner layers. The meltstream may be multiplied by performing thedividing, flattening and recombining a number of times to produce asingle melt stream consisting of a plurality of sublayers of thecomponent materials. In this two material embodiment, the composition ofthe layers will alternate between the two materials. The output from thelayer generation system passes through a neck 282 and is injected into amold to form a preform or a coating.

[0220] A system such as that in FIG. 25 to generate a lamellarmeltstream may be used in place of one or both of the injectors in theovermolding process and apparatus described above. Alternatively, abarrier preform could be formed using a single injection of a LIMmeltstream if the meltstream comprised barrier material. If a preform ismade exclusively from a LIM meltstream or is made having an inner layerwhich was made from a LIM meltstream, and the container made therefromis to be in contact with edibles, it is preferred that all materials inthe LIM meltstream have FDA approval.

[0221] In one preferred embodiment, a preform of the type in FIG. 4 ismade using an inject-over-inject process wherein a lamellar meltstreamis injected into the barrier coating cavities. Such a process, in whicha preform is overmolded with a lamellar meltstream, can be calledLIM-over-inject. In a LIM-over-inject process to create a preform fromwhich a beverage bottle is made by blow molding, the first or innerlayer 72 is preferably virgin PET, and the LIM meltstream is preferablya barrier material, such as PHAE, and recycled PET. Recycled PET is usedin the outer layer 74 because it will not be in contact with edibles andit is cheaper to use to make up the bulk of a container than is virginPET or most barrier materials.

[0222]FIG. 4A shows an enlarged view of a wall section 3 of a preform ofthe type in FIG. 4 made by a LIM over inject process. The inner layer 72is a single material, but the outer layer 74 is comprised of a pluralityof microlayers formed by the LIM process.

[0223] An exemplary process to make such a preform is as follows.Recycled polyethylene terephthalate is applied through a feed hopper 272to a first cylinder 276, while simultaneously, a barrier material isapplied through a second feed hopper 274 to a second cylinder 278. Thetwo materials are coextruded at rates to provide two-layer lamellarmeltstream comprising preferably 60-95 wt. % recycled polyethyleneterephthalate and preferably 5-40 wt. % barrier material. The lamellarmeltstream is applied to the layer generation system 280 in which alamellar melt stream comprising the two materials is formed by dividing,flattening and recombining the meltstream, preferably at least twice.This lamellar melt stream exits at 282 and is then injected into a mold,such as that depicted in FIG. 9. Preferably, the lamellar melt stream isinjected into the preform coating cavities 120 of in an overmoldingapparatus such as that in FIGS. 10 and 11 over a preform, to form aLIM-over-inject coated preform comprising a barrier layer consisting ofalternating microlayers of barrier material and recycled PET.

[0224] In another exemplary process, virgin PET is applied through afeed hopper 272 to a first cylinder 276, while simultaneously, B-010 isapplied through a second feed hopper 274 to a second cylinder 278. Thetwo polymers are coextruded at rates to provide a meltstream comprisingpreferably 60-95 wt. % virgin polyethylene terephthalate and preferably5-40 wt. % B-010. The two layer meltstream is applied to a layergeneration system 280 in which a lamellar melt stream comprising the twomaterials is formed by dividing flattening and recombining themeltstream, preferably at least twice. This lamellar melt stream exitsat 282 and is then injected into the preform molding cavities 156, 256of any of the overmolding apparatus 150, 250 described above. Thisinitial LIM preform is overinjected with recycled PET in the preformcoating cavities 158, 258 to produce a preform with an inner layerconsisting of alternating microlayers of barrier material and virginPET, and an outer layer of recycled PET. Such a process may be calledinject-over-LIM.

[0225] In the multilayer preform, LIM-over-inject or inject-over-LIMembodiments, the lamellar injection system can be used to advantage toprovide a plurality of alternating and repeating sublayers, preferablycomprised of PET and a barrier material. The multiple layers of theseembodiments of the invention offers a further safeguard againstpremature diffusion of gases through the sidewall of the beveragecontainer or other food product container.

H. Improving Mold Performance

[0226] As discussed above, the mold halves have an extensive coolingsystem comprising circulating coolant throughout the mold in order toconduct heat away and thus enhance the mold's heat absorptionproperties. With next reference to FIG. 26, which is a cross-section ofa mold mandrel 298 and cavity 300 having features in accordance with thepresent invention, the mold cooling system can be optimized for the moldcavities by arranging cooling tubes 302 in a spiral around the moldcavity 300 and just below the surface 304. The rapid cooling enabled bysuch a cooling system helps avoid crystallization of the PET layerduring cooling. Also, the rapid cooling decreases the production cycletime by allowing injected preforms to be removed from the mold cavitiesquickly so that the mold cavity 300 may be promptly reused.

[0227] As discussed above, the gate area 306 of the mold cavity 300 isespecially pivotal in determining cycle time. The void space near thegate 308, which will make up the molded preform's base end 304, receivesthe last portion of the melt stream to be injected into the mold cavity300. Thus, this portion is the last to begin cooling. If the PET layerhas not sufficiently cooled before the overmolding process takes place,the force of the barrier material melt entering the mold may wash awaysome of the PET near the gate area 308. To speed cooling in the gatearea of the mold cavity in order to decrease cycle time, inserts 310 ofan especially high heat transfer material such as Ampcoloy can bedisposed in the mold in the gate area 308. These Ampcoloy inserts 310will withdraw heat at an especially fast rate. To enhance and protectthe Ampcoloy inserts 310, a thin layer of titanium nitride or hardchrome may be deposited on the surface 312 of the Ampcoloy to form ahard surface. Such a deposited surface would be preferably between only0.001 and 0.01 inches thick and would most preferably be about 0.002inches thick.

[0228] As discussed above, the mandrel 298 is especially important inthe cooling process because it directly cools the inner PET layer. Toenhance the cooling effect of the mandrel 298 on the inner surface ofthe preform and especially to enhance the cooling effect of the mandrel298 at the preform's gate area/base end 314, the mandrel 298 ispreferably substantially hollow, having a relatively thin uniform wall320, as shown in FIG. 26. Preferably, this uniform thickness is between0.1 inch and 0.3 inches and is most preferably about 0.2 inches. It isparticularly important that the wall 320 at the base end 322 of themandrel 298 is no thicker than the rest of the mandrel wall 314 becausethe thin wall aids in rapidly communicating heat away from the moltengate area 314 of the injected preform.

[0229] To further enhance the mandrel's cooling capability, coolingwater may be supplied in a bubbler arrangement 330. A core tube 332 isdisposed centrally in the mandrel 298 and delivers chilled coolant C tothe base end 322 thereof. Since the base end 322 is the first point ofthe mandrel 298 contacted by this coolant C, the coolant is coldest andmost effective at this location. Thus, the gate area 314 of the injectedpreform is cooled at a faster rate than the rest of the preform. Coolantinjected into the mandrel at the base end 322 proceeds along the lengthof the mandrel 298 and exits through an output line 334. A plurality ofribs 336 are arranged in a spiral pattern around the core 332 to directcoolant C along the mandrel wall.

[0230] Another way to enhance cooling of the preform's gate area wasdiscussed above and involves forming the mold cavity so that the innerPET layer is thinner at the gate area than at the rest of the injectedpreform as shown in FIG. 4. The thin gate area thus cools quickly to asubstantially solid state and can be quickly removed from the first moldcavity, inserted into the second mold cavity, and have a layer ofbarrier material injected thereover without causing washing of the PET.

[0231] In the continuing effort to reduce cycle time, injected preformsare removed from mold cavities as quickly as possible. However, it maybe appreciated that the newly injected material is not necessarily fullysolidified when the injected preform is removed from the mold cavity.This results in possible problems removing the preform from the cavity300. Friction or even a vacuum between the hot, malleable plastic andthe mold cavity surface 304 can cause resistance resulting in damage tothe injected preform when an attempt is made to remove it from the moldcavity 300.

[0232] Typically, mold surfaces are polished and extremely smooth inorder to obtain a smooth surface of the injected part. However, polishedsurfaces tend to create surface tension along those surfaces. Thissurface tension may create friction between the mold and the injectedpreform which may result in possible damage to the injected preformduring removal from the mold. To reduce surface tension, the moldsurfaces are preferably treated with a very fine sanding device toslightly roughen the surface of the mold. Preferably the sandpaper has agrit rating between about 400 and 700. More preferably a 600 gritsandpaper is used. Also, the mold is preferably sanded in only alongitudinal direction, further facilitating removal of the injectedpreform from the mold.

[0233] During injection, air is pushed out of the mold cavity 300 by theinjected meltstream. As a result, a vacuum may develop between theinjected preform and the mold cavity wall 304. When the injected preformis removed from the cavity 300, the vacuum may resist removal, resultingin damage to the not-fully-solidified preform. To defeat the vacuum, anair insertion system 340 may be employed. With additional reference toFIGS. 27 and 28, an embodiment of an air insertion system 340 isprovided. At a joint 342 of separate members of the mold cavity 300, anotch 344 is preferably formed circumferentially around and opening intothe mold cavity 300. The notch 344 is preferably formed by a step 346 ofbetween 0.002 inches and 0.005 inches and most preferably about 0.003inches in depth. Because of its small size, the notch 344 will not fillwith plastic during injection but will enable air A to be introducedinto the mold cavity 300 to overcome the vacuum during removal of theinjected preform from the mold cavity 300. An air line 350 connects thenotch 344 to a source of air pressure and a valve (not shown) controlsthe supply of air A. During injection, the valve is closed so that themelt fills the mold cavity 300 without air resistance. When injection iscomplete, the valve opens and a supply of air is delivered to the notch344 at a pressure between about 75 psi and 150 psi and most preferablyabout 100 psi. The supply of air defeats any vacuum that may formbetween the injected preform and the mold cavity, aiding removal of thepreform. Although the drawings show only a single air supply notch 344in the mold cavity 300, any number of such notches may be provided andin a variety of shapes depending on the size and shape of the mold.

[0234] While some of the above-described improvements to moldperformance are specific to the method and apparatus described herein,those of skill in the art will appreciate that these improvements mayalso be applied in many different types of plastic injection moldingapplications and associated apparatus. For instance, use of Ampcoloy ina mold may quicken heat removal and dramatically decrease cycle timesfor a variety of mold types and melt materials. Also, roughening of themolding surfaces and provides air pressure supply systems may ease partremoval for a variety of mold types and melt materials.

I. Formation of Preferred Containers by Blow Molding

[0235] The barrier-coated containers preferably produced by blow-moldingthe barrier-coated preforms, the creation of which is disclosed above.The barrier-coated preforms can be blow-molded using techniques andconditions very similar, if not identical, to those by which uncoatedPET preforms are blown into containers. Such techniques and conditionsfor blow-molding monolayer PET preforms into bottles are well known tothose skilled in the art and can be used or adapted as necessary.

[0236] Generally, in such a process, the preform is heated to atemperature of preferably 80 to 120° C., more preferably 100 to 105° C.,and given a brief period of time to equilibrate. After equilibration, itis stretched to a length approximating the length of the finalcontainer. Following the stretching, pressurized air is forced into thepreform which acts to expand the walls of the preform to fit the mold inwhich it rests, thus creating the container.

J. Testing of Laminate Bottles

[0237] Several bottles were made according to the overmolding processesof the present invention, having varying amounts of IPA in the PET, andusing PHAE as the barrier material. Control bottles were also made fromPET having no IPA therein.

[0238] The test bottles were made by blow-molding preforms made by theovermolding process described above. An impact test was then performedon the bottles, whereby the sidewall (body portion) of each bottle wasstruck by an impacting force. The bottles were then observed for signsof physical damage, most importantly delamination of the laminatematerial in the sidewall of the bottle.

[0239] It was found that the bottles having inner PET layers havinghigher levels of IPA experienced less delamination when subjected to theimpact test than laminates having lower levels of IPA, which still faredbetter than those bottles made from PET having no IPA at all. Thus, itis shown that better adhesion between the layers of the laminate isachieved when IPA-PET is used in making laminates with phenoxymaterials.

[0240] Although the present invention has been described in terms ofcertain preferred embodiments, and certain exemplary methods, it is tobe understood that the scope of the invention is not to be limitedthereby. Instead, Applicant intends that the scope of the invention belimited solely by reference to the attached claims, and that variationson the methods and materials disclosed herein which are apparent tothose of skill in the art will fall within the scope of Applicant'sinvention.

What is claimed is:
 1. A laminate comprising at least a first layer ofpolyethylene terephthalate directly adhered to a second layer ofthermoplastic material, wherein said second layer of thermoplasticmaterial is selected from the group consisting of Copolyester BarrierMaterials, Phenoxy-type Thermoplastics, Polyamides, polyethylenenaphthalate, polyethylene naphthalate copolymers, polyethylenenaphthalate/polyethylene terephthalate blends, polyethyleneterephthalate and combinations thereof, and said polyethyleneterephthalate in the first layer has an isophthalic acid content of atleast about 2% by weight.
 2. A laminate according to claim 1, whereinthe isophthalic acid content of the polyethylene terephthalate in thefirst layer is about 2% -10% by weight.
 3. A laminate according to claim1, wherein the isophthalic acid content of the polyethyleneterephthalate in the first layer is about 4% -5% by weight.
 4. Alaminate according to claim 1, wherein the isophthalic acid content ofthe polyethylene terephthalate in the first layer is about 3% -8% byweight.
 5. A laminate according to claim 1, wherein the isophthalic acidcontent of the polyethylene terephthalate in the first layer is about 5%-10% by weight.
 6. A laminate according to claim 1, wherein the secondlayer of thermoplastic material is a poly(hydroxyamino ether).
 7. Alaminate according to claim 1, wherein the second layer of thermoplasticmaterial is a Copolyester Barrier Material.
 8. A laminate according toclaim 1, wherein the second layer of thermoplastic material is aPolyamide comprising a polyamide and 1-10% polyethylene terephthalate.9. A laminate according to claim 1, wherein the second layer ofthermoplastic material is polyethylene terephthalate comprising recycledor post-consumer polyethylene terephthalate.
 10. A laminate in the formof a preform comprising a neck portion and a body portion, wherein atleast said body portion comprises: at least a first layer comprisingpolyethylene terephthalate having an isophthalic acid content of atleast about 2% by weight bound directly to a second layer comprising athermoplastic material, wherein said thermoplastic material is selectedfrom the group consisting of Copolyester Barrier Materials, Phenoxy-typeThermoplastics, Polyamides, polyethylene naphthalate, polyethylenenaphthalate copolymers, polyethylene naphthalate/polyethyleneterephthalate blends, and combinations thereof.
 11. A laminate in theform of a preform according to claim 10, wherein the body portion of thepreform comprises a wall portion and an end cap and the first layer isthinner in the end cap than in the wall portion and the second layer isthicker in the end cap than in the wall portion.
 12. A laminateaccording to claim 11, wherein the first layer faces the preforminterior.
 13. A laminate according to claim 10, wherein the isophthalicacid content of the polyethylene terephthalate is about 2% -10% byweight.
 14. A laminate according to claim 10, wherein the isophthalicacid content of the polyethylene terephthalate is about 4% -5% byweight.
 15. A laminate according to claim 10, wherein the barriermaterial is a poly(hydroxyamino ether).
 16. A laminate according toclaim 10, wherein the barrier material is a Copolyester BarrierMaterial.
 17. A laminate according to claim 10, wherein the barriermaterial is a Polyamide comprising a polyamide and 1-10% polyethyleneterephthalate.
 18. A laminate in the form of a container comprising aneck portion and body portion, wherein at least said body portioncomprises: at least one layer comprising polyethylene terephthalatehaving an isophthalic acid content of at least about 2% by weight; andat least one layer comprising a barrier material bound directly thereto,wherein said barrier material is selected from the group consisting ofCopolyester Barrier Materials, Phenoxy-type Thermoplastics, Polyarnides,polyethylene naphthalate, polyethylene naphthalate copolymers,polyethylene naphthalate/polyethylene terephthalate blends, andcombinations thereof.
 19. A laminate according to claim 18, wherein theisophthalic acid content of the polyethylene terephthalate is about 2%-10% by weight.
 20. A laminate according to claim 18, wherein theisophthalic acid content of the polyethylene terephthalate is about 4%-5% by weight.
 21. A laminate according to claim 18, wherein the barriermaterial is a poly(hydroxyamino ether).
 22. A laminate according toclaim 18, wherein the barrier material is a Copolyester BarrierMaterial.
 23. A laminate according to claim 18, wherein the barriermaterial is a Polyamide comprising a polyamide and 1-10% polyethyleneterephthalate.